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eSolutions Manual - Powered by Cognero Page 1 the polynomial cannot be factored using integers,...

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Factor each polynomial, if possible. If the polynomial cannot be factored using integers, write prime . 1. 3x 2 + 17x + 10 SOLUTION: In this trinomial, a = 3, b = 17 and c = 10, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 3(10) or 30 and identify the factors with a sum of 17. The correct factors are 2 and 15. So, 3x 2 + 17x + 10 = (3x + 2) (x +5). Factors of 30 Sum 1, 30 31 2, 15 17 5, 6 30 2 eSolutions Manual - Powered by Cognero Page 1 8 - 7 Solving ax^2 + bx + c = 0
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  • Factor each polynomial, if possible. If the polynomial cannot be factored using integers, write prime .

    1.3x2 + 17x + 10

    SOLUTION:

    In this trinomial, a = 3, b = 17 and c = 10, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 3(10) or 30 and identify the factors with a sum of 17.

    The correct factors are 2 and 15.

    So, 3x2 + 17x + 10 = (3x + 2) (x +5).

    Factors of 30 Sum 1, 30 31 2, 15 17 5, 6 30

    2.2x2 + 22x + 56

    SOLUTION:

    The GCF of the terms 2x2, 22x, and 56 is 2. Factor this first.

    2x2

    +22x + 56 = 2(x2 + 11x+28)Distributive Property

    In the trinomial, a = 1, b = 11 and c = 28, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 1(28) or 28 and identify the factors with a sum of 11.

    The correct factors are 4 and 7.

    So, 2x2 + 22x + 56= 2(x + 4)(x + 7).

    Factors of 28 Sum 1, 28 29 2, 14 16 4, 7 11

    3.5x2 3x + 4

    SOLUTION:

    In this trinomial, a = 5, b = 3 and c = 4, so m + p is negative and mp is positive. Therefore, m and p must have different signs. List the factors of 5(4) or 20 and identify the factors with a sum of 3.

    There are no factors of 20 with a sum of 3. This trinomial is prime.

    Factors of 20 Sum 1, 20 19 1, 20 19 2, 10 8 2, 10 8 4, 5 1 4, 5 1

    4.3x2 11x 20

    SOLUTION:

    In this trinomial, a = 3, b = 11 and c = 20, so m + p is negative and mp is negative. Therefore, m and p must have different signs. List the factors of 3(20) or 60 and identify the factors with a sum of 11.

    The correct factors are 4 and 15 .

    So, 3x2 11x 20 = (3x +4)(x 5).

    Factors of 60 Sum 1, 60 59 1, 60 59 2, 30 28 2, 30 28 3, 20 17 3, 20 17 4, 15 11 4, 15 11 5, 12 7 5, 12 7 6, 10 4 6, 10 4

    Solve each equation. Confirm your answers using a graphing calculator.

    5.2x2 + 9x + 9 = 0

    SOLUTION:Factor the trinomial.

    Solve the equation using the Zero Product Property. (2x + 3)(x + 3) = 0

    The roots are and3.

    Confirm the roots using a graphing calculator. Let Y1 = 2x2 + 9x + 9 and Y2 = 0. Use the intersect option from the

    CALC menu to find the points intersection.

    Thus, the solutions are and3.

    6.3x2 + 17x + 20 = 0

    SOLUTION:Factor the trinomial.

    Solve the equation using the Zero Product Property. (3x + 5)(x + 4) = 0

    The roots are and4 or about 1.667 and 4.

    Confirm the roots using a graphing calculator. Let Y1 = 3x2 + 17x + 20 and Y2 = 0. Use the intersect option from

    the CALC menu to find the points intersection.

    Thus, the solutions are and4.

    7.3x2 10x + 8 = 0

    SOLUTION:Factor the trinomial.

    Solve the equation using the Zero Product Property.

    The roots are and2orabout1.333and2.

    Confirm the roots using a graphing calculator. Let Y1 = 3x2 10x + 8 and Y2 = 0. Use the intersect option from the

    CALC menu to find the points intersection.

    Thus, the solutions are and2.

    8.2x2 17x + 30 = 0

    SOLUTION:Factor the trinomial.

    Solve the equation using the Zero Product Property. (2x 5) (x 6) = 0

    The roots are and6.

    Confirm the roots using a graphing calculator. Let Y1 = 2x2 17x + 30 and Y2 = 0. Use the intersect option from

    the CALC menu to find the points intersection.

    Thus, the solutions are and6.

    9.CCSSMODELING Ken throws the discus at a school meet.

    a. What is the initial height of the discus? b. After how many seconds does the discus hit the ground?

    SOLUTION:a. The initial height of the discus is for the time t = 0.

    The initial height of the discus is 5 feet. b. When the discus hits the ground, the height will be zero, so h = 0. Substitute 0 for h in the equation and factor the trinomial.

    The solutions to the equation are and . Since time cannot be negative, the discus will hit the ground after or

    2.5 seconds. Check by substituting 2.5 in for x in the original equation.

    Therefore, the discus will hit the ground after 2.5 seconds.

    Factor each polynomial, if possible. If the polynomial cannot be factored using integers, write prime .

    10.5x2 + 34x + 24

    SOLUTION:

    In this trinomial, a = 5, b = 34 and c = 24, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 5(24) or 120 and identify the factors with a sum of 34.

    The correct factors are 4 and 30.

    So, 5x2 + 34x + 24= (5x + 4)(x + 6).

    Factors of 120 Sum 1, 120 121 2, 60 62 3, 40 43 4, 30 34 5, 24 29 6, 20 26 8, 15 23 10, 12 22

    11.2x2 + 19x + 24

    SOLUTION:

    In this trinomial, a = 2, b = 19 and c = 24, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 2(24) or 48 and identify the factors with a sum of 19.

    The correct factors are 3 and 16.

    So, 2x2 + 19x + 24= (2x + 3)(x + 8).

    Factors of 48 Sum 1, 48 49 2, 24 26 3, 16 19 4, 12 16 6, 8 14

    12.4x2 + 22x + 10

    SOLUTION:

    The GCF of the terms 4x2, 22x, and 10 is 2. Factor this first.

    4x2 + 22x + 10 = 2(2x

    2 + 11x+5)Distributive Property

    In the trinomial, a = 2, b = 11 and c = 5, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the factors of 2(5) or 10 and identify the factors with a sum of 11.

    The correct factors are 1 and 10.

    So, 4x2 + 22x + 10= 2(2x + 1)(x + 5).

    Factors of 10 Sum 1, 10 11 2, 5 7

    13.4x2 + 38x + 70

    SOLUTION:

    The GCF of the terms 4x2, 38x, and 70 is 2. Factor this first.

    4x2

    +38x + 70 = 2(2x2 + 19x+35)Distributive Property

    In the trinomial, a = 2, b = 19 and c = 35, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 2(35) or 70 and identify the factors with a sum of 19.

    The correct factors are 5 and 14.

    So, 4x2 + 38x + 70= 2(2x + 5)(x + 7).

    Factors of 70 Sum 1, 70 71 2, 35 37 5, 14 19 7, 10 17

    14.2x2 3x 9

    SOLUTION:

    In this trinomial, a = 2, b = 3 and c = 9, so m + p is negative and mp is negative. Therefore, m and p must have different signs. List the factors of 2(9) or 18 and identify the factors with a sum of 3.

    The correct factors are 3 and 6.

    So, 2x2 3x 9= (2x + 3)(x 3).

    Factors of 18 Sum 1, 18 17 1, 18 17 2, 9 7 2, 9 7 3, 6 3 3, 6 3

    15.4x2 13x + 10

    SOLUTION:

    In this trinomial, a = 4, b = 13 and c = 10, so m + p is negative and mp is positive. Therefore, m and p must both be negative. List the negative factors of 4(10) or 40 and identify the factors with a sum of 13.

    The correct factors are 5 and 8.

    So, 4x2 13x + 10= (4x 5)(x 2).

    Factors of 40 Sum 1, 40 41 2, 20 22 4, 10 14 5, 8 13

    16.2x2 + 3x + 6

    SOLUTION:

    In this trinomial, a = 2, b = 3, and c = 6, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 2(6) or 12 and identify the factors with a sum of 3.

    There are no factors of 12 with a sum of 3.

    So, 2x2 + 3x + 6 is prime.

    Factors of 12 Sum 1, 12 13 2, 6 8 3, 4 7

    17.5x2 + 3x + 4

    SOLUTION:

    In this trinomial, a = 5, b = 3, and c = 4, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 5(4) or 20 and identify the factors with a sum of 3.

    There are no factors of 20 with a sum of 3.

    So, 5x2 + 3x + 4 is prime.

    Factors of 20 Sum 1, 20 21 2, 10 12 4, 5 9

    18.12x2 + 69x + 45

    SOLUTION:

    The GCF of the terms 122x2, 69x, and 45 is 3. Factor this first.

    12x2

    +69x + 45 = 3(4x2 + 23x+15)Distributive Property

    In the trinomial, a = 4, b = 23 and c = 15, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 4(15) or 60 and identify the factors with a sum of 23.

    The correct factors are 3 and 20.

    So, 12x2 + 69x + 45= 3(4x + 3)(x + 5).

    Factors of 60 Sum 1, 60 61 2, 30 32 3, 20 23 4, 15 19 5, 12 17 6, 10 60

    19.4x2 5x + 7

    SOLUTION:

    In this trinomial, a = 4, b = 5, and c = 7, so m + p is negative and mp is positive. Therefore, m and p must both be negative. List the negative factors of 4(7) or 28 and identify the factors with a sum of 5.

    There are no factors of 28 with a sum of 11.

    So, 4x2 5x + 7 is prime.

    Factors of 28 Sum 1,28 29 2, 14 16 4, 7 11

    20.5x2 + 23x + 24

    SOLUTION:

    In this trinomial, a = 5, b = 23 and c = 24, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 5(24) or 120 and identify the factors with a sum of 23.

    The correct factors are 8 and 15.

    So, 5x2 + 23x + 24= (5x + 8)(x + 3).

    Factors of 120 Sum 1, 120 121 2, 60 62 3, 40 43 4, 30 34 5, 24 29 6, 20 26 8, 15 23 10, 12 22

    21.3x2 8x + 15

    SOLUTION:

    In this trinomial, a = 3, b = 8, and c = 15, so m + p is negative and mp is positive. Therefore, m and p must both be negative. List the factors of 3(15) or 45 and identify the factors with a sum of 8.

    There are no factors of 45 with a sum of 8.

    So, 3x2 8x + 15 is prime.

    Factors of 45 Sum 1,45 46 3, 15 18 5, 9 14

    22.SHOTPUT An athlete throws a shot put with an initial upward velocity of 29 feet per second and from an initial height of 6 feet. a. Write an equation that models the height of the shot put in feet with respect to time in seconds. b. After how many seconds will the shot put hit the ground?

    SOLUTION:

    a. A model for the vertical motion of a projected object is given by h = 16t2 + vt + h0, where h is the height in feet,

    t is the time in seconds, v is the initial velocity in feet per second, and h0 is the initial height in feet. The initial velocity

    of the shot put, v, is 29 feet per second. The initial height of the shot put, h0, is 6 feet.

    So, the equation h = 16t2 + 29t + 6 models the height of the shot put in feet with respect to the time in seconds. b. When the shot put hits the ground, the height will be zero, so h = 0.

    The roots are and 2. Because time cannot be negative, the shot put will hit the ground after 2 seconds.

    Solve each equation. Confirm your answers using a graphing calculator.

    23.2x2 + 9x 18 = 0

    SOLUTION:Factor the trinomial.

    The roots are and6.

    Confirm the roots using a graphing calculator. Let Y1 = 2x2 +9x 18 and Y2 = 0. Use the intersect option from the

    CALC menu to find the points intersection.

    Thus, the solutions are and6.

    24.4x2 + 17x + 15 = 0

    SOLUTION:Factor the trinomial then solve the equation using the Zero Product Property. .

    The roots are and3.

    Confirm the roots using a graphing calculator. Let Y1 = 4x2 +17x + 15 and Y2 = 0. Use the intersect option from

    the CALC menu to find the points intersection.

    Thus, the solutions are and3.

    25.3x2 + 26x = 16

    SOLUTION:Factor the trinomial, then solve the equation using the Zero Product Property.

    The roots are and8.

    Confirm the roots using a graphing calculator. Let Y1 = -3x2 +26x and Y2 = 16. Use the intersect option from the

    CALC menu to find the points intersection.

    Thus, the solutions are and8.

    26.2x2 + 13x = 15

    SOLUTION:Factor the trinomial, then solve the equation using the Zero Product Property.

    The roots are and5.

    Confirmtherootsusingagraphingcalculator.LetY1 = -2x2 +13x and Y2 = 15. Use the intersect option from the CALC menu to find the points intersection.

    Thus, the solutions are and5.

    27.3x2 + 5x = 2

    SOLUTION:Factor the trinomial, then solve the equation using the Zero Product Property.

    The roots are and2.

    Confirm the roots using a graphing calculator. Let Y1 = -3x2 +5x and Y2 = -2. Use the intersect option from the

    CALC menu to find the points intersection.

    Thus, the solutions are and2.

    28.4x2 + 19x = 30

    SOLUTION:Factor the trinomial, then solve the equation using the Zero Product Property.

    The roots are and6.

    Confirm the roots using a graphing calculator. Let Y1 = -4x2 +19x and Y2 = -30. Use the intersect option from the

    CALC menu to find the points intersection.

    Thus, the solutions are and6.

    29.BASKETBALL When Jerald shoots a free throw, the ball is 6 feet from the floor and has an initial upward velocity of 20 feet per second. The hoop is 10 feet from the floor. a. Use the vertical motion model to determine an equation that models Jeralds free throw. b. How long is the basketball in the air before it reaches the hoop? c. Raymond shoots a free throw that is 5 foot 9 inches from the floor with the same initial upward velocity. Will the ball be in the air more or less time? Explain.

    SOLUTION:

    a. A model for the vertical motion of a projected object is given by h = 16t2 + vt + h0, where h is the height in feet,

    t is the time in seconds, v is the initial velocity in feet per second, and h0 is the initial height in feet. The initial velocity

    of the basketball, v, is 20 feet per second. The initial height of the basketball, h0, is 6 feet. The height of the hoop, h,

    is 10 feet.

    So, the equation 10 = 16t2 + 20t + 6 models Jeralds free throw.

    b.

    The roots are and 1. The basketball takes second to reach a height of 10 feet on its way up. The basketball

    takes 1 second to reach a height of 10 feet on its way down. So, the basketball will be in the air 1 second before it reaches the hoop. c. The ball will be in the air less time because it starts closer to the ground so the shot will not have as far to fall.

    30.DIVING Ben dives from a 36-foot platform. The equation h = 16t2 + 14t + 36 models the dive. How long will it take Ben to reach the water?

    SOLUTION:When Ben reaches the pool, his height, h will be 0.

    The roots are and 2. Because time cannot be negative, Ben will reach the water after 2 seconds.

    31.NUMBERTHEORY Six times the square of a number x plus 11 times the number equals 2. What are possible values of x?

    SOLUTION:

    Let x = a number. Then, 6x2 +11x = 2.

    The possible values of x are 2 or .

    Factor each polynomial, if possible. If the polynomial cannot be factored using integers, write prime .

    32.6x2 23x 20

    SOLUTION:First factor the number 1 out of each term in the polynomial.

    Then factor the trinomial 6x2 + 23x + 20.

    In this trinomial, a = 6, b = 23 and c = 20, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 6(20) or 120 and identify the factors with a sum of 23.

    The correct factors are 8 and 15.

    So, 6x2 23x 20= (2x + 5)(3x + 4).

    Factors of 120 Sum 1, 120 121 2, 60 62 3, 40 43 4, 30 34 5, 24 29 6, 20 26 8, 15 23 10, 12 22

    33.4x2 15x 14

    SOLUTION:First factor the number 1 out of each term in the polynomial.

    4x2 15x 14 = 1(4x2 + 15x + 14)

    Then factor the trinomial 4x2 + 15x + 14.

    In this trinomial, a = 4, b = 15 and c = 14, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 4(14) or 56 and identify the factors with a sum of 15.

    The correct factors are 7 and 8.

    So, 4x2 15x 14 = (x + 2)(4x + 7).

    Factors of 56 Sum 1, 56 57 2, 28 30 4, 14 18 7, 8 115

    34.5x2 + 18x + 8

    SOLUTION:First factor the number 1 out of each term in the polynomial.

    5x2 + 18x + 8 = 1(5x2 18x 8)

    Then factor the trinomial 5x2 18x 8.

    In this trinomial, a = 5, b = 18 and c = 8, so m + p is negative and mp is negative. Therefore, m and p must have different signs. List the factors of 5(8) or 40 and identify the factors with a sum of 18.

    The correct factors are 20 and 2 .

    So, 5x2 + 18x + 8 = (x 4)(5x + 2).

    Factors of 40 Sum 1, 40 39 1, 40 39 2, 20 18 2, 20 18 4, 10 6 4, 10 6 5, 8 3 5, 8 3

    35.6x2 + 31x 35

    SOLUTION:First factor the number 1 out of each term in the polynomial.

    6x2 + 31x 35 = 1(6x2 31x + 35)

    Then factor the trinomial 6x2 31x + 35.

    In this trinomial, a = 6, b = 31 and c = 35, so m + p is negative and mp is positive. Therefore, m and p must both be negative. List the negative factors of 6(35) or 210 and identify the factors with a sum of 31.

    The correct factors are 21 and 10.

    So, 6x2 + 31x 35 = (2x 7)(3x 5).

    Factors of 210 Sum 1, 210 211 2, 105 107 3, 70 73 5, 42 47 6, 35 41 7, 30 37 10, 21 31 14, 15 29

    36.4x2 + 5x 12

    SOLUTION:First factor the number 1 out of each term in the polynomial. 4x2 + 5x 12 = 1(4x2 5x + 12)

    Then factor the trinomial 4x2 5x + 12.

    In this trinomial, a = 4, b = 5 and c = 12, so m + p is negative and mp is positive. Therefore, m and p must both be negative. List the negative factors of 4(12) or 48 and identify the factors with a sum of 5.

    There are no factors of 48 with a sum of 5. So, 4x2 + 5x 12 is prime.

    Factors of 48 Sum 1, 48 49 2, 24 26 3, 16 19 4, 12 16 6, 8 14

    37.12x2 + x + 20

    SOLUTION:First factor the number 1 out of each term in the polynomial.

    12x2 + x + 20 = 1(12x2 x 20)

    Then factor the trinomial 12x2 x 20.

    In this trinomial, a = 12, b = 1 and c = 20, so m + p is negative and mp is negative. Therefore, m and p must have different signs. List the factors of 12(20) or 240 and identify the factors with a sum of 1.

    The correct factors are 16 and 15.

    So, 12x2 + x + 20 = (4x + 5)(3x 4).

    Factors of 240 Sum 1, 240 239 1, 240 239 2, 120 118 2, 120 118 3, 80 77 3, 80 77 4, 60 56 4, 60 56 5, 48 43 5, 48 43 6, 40 34 6, 40 34 8, 30 22 8, 30 22 10, 24 14 10, 24 14 12, 20 8 12, 20 8 15, 16 1 15, 16 1

    38.URBANPLANNING The city has commissioned the building of a rectangular park. The area of the park can be

    expressed as 660x2 + 524x + 85. Factor this expression to find binomials with integer coefficients that represent

    possible dimensions of the park. If x = 8, what is a possible perimeter of the park?

    SOLUTION:

    So, (22x + 5)(30x + 17) represent the possible dimensions of the park.

    Evaluate each dimension when x = 8 to find the possible length and width of the park when x = 8.

    A possible perimeter of the park is 876 units.

    39.MULTIPLEREPRESENTATIONS In this problem, you will explore factoring a special type of polynomial. a.GEOMETRIC Draw a square and label the sides a. Within this square, draw a smaller square that shares a vertex with the first square. Label the sides b. What are the areas of the two squares? b.GEOMETRIC Cut and remove the small square. What is the area of the remaining region? c.ANALYTICAL Draw a diagonal line between the inside corner and outside corner of the figure, and cut along this line to make two congruent pieces. Then rearrange the two pieces to form a rectangle. What are the dimensions? d.ANALYTICAL Write the area of the rectangle as the product of two binomials.

    e.VERBAL Complete this statement: a2 b2 = Why is this statement true?

    SOLUTION:a.

    The area of a square is found using the formula A = s2. So, the area of the larger square is a

    2 and the area of the

    smaller square is b2.

    b.

    To find the area of the remaining region, subtract the area of the smaller square from the area of the larger square.

    So, the area of the remaining region is a2 b

    2.

    c.

    The width is a b and the length is a + b. d.

    e . The figure with area a2 b2 and the rectangle with area (a b)(a + b) have the same area, so a2 b2 = (a b)(a + b).

    40.CCSSCRITIQUE Zachary and Samantha are solving 6x2 x = 12. Is either of them correct? Explain your

    reasoning.

    SOLUTION:Sample answer: By the Zero Product Property, the equation must be set equal to zero before it can be factored. Then each of the factors can be set equal to zero and solved for x.

    So, Samantha is correct.

    41.REASONING A square has an area of 9x2 + 30xy + 25y2 square inches. The dimensions are binomials with positive integer coefficients. What is the perimeter of the square? Explain.

    SOLUTION:

    The area of the square equals 9x2 + 30xy + 25y

    2.

    So, the length of each side of the square is (3x + 5y) inches.

    The perimeter of the square is (12x + 20y) inches.

    42.CHALLENGE Find all values of k so that 2x2 + kx + 12 can be factored as two binomials using integers.

    SOLUTION:The values for k must be the sum of two negative factors or two positive factors of 2(12) or 24.

    Factors of 24 Possible Values for k 1, 24 25

    1, 24 25 2, 12 14

    2, 12 14 3, 8 11

    3, 8 11 4, 6 10

    4, 6 10

    43.WRITING IN MATH What should you consider when solving a quadratic equation that models a real-world situation?

    SOLUTION:Sample answer: A quadratic equation may have zero, one, or two solutions. If there are two solutions, you must consider the context of the situation to determine whether one or both solutions answer the given question. For example: Timecannotbenegative. A solution stating that a person ran 60 miles per hour is unrealistic.

    44.WRITINGINMATH Explain how to determine which values should be chosen for m and p when factoring a

    polynomial of the form ax2 + bx + c.

    SOLUTION:

    Sample answer: If the trinomial factors, then ax2 + bx + c = ax2 + mx + px + c where m and n are two integers thathave a product equal to ac and a sum equal b. For example, given the trinomial 3x

    2 + 14x + 15, a = 3, b = 14, and c = 15. Find two integers such that mp = 3(15) or 45 and m + p =14.Since59=45and5+9=14,thevaluesofthevariables could be m = 5 and p = 9. Check to see if the trinomial factors using these values for m and p .

    45.GRIDDEDRESPONSE Savannah has two sisters. One sister is 8 years older than her, and the other sister is 2 years younger than her. The product of Savannahs sistersages is 56. How old is Savannah?

    SOLUTION:Let s = Savannahs age. Then, s + 8 = the age of her older sister and s 2 = the age of her younger sister.

    The roots are 12 and 6. Savannahs age cannot be negative. So, Savannah is 6 years old.

    46.What is the product of a3b

    5 and a

    5b

    2?

    A a8b

    7

    B a2b

    3

    C a8b

    3

    D a2b

    7

    SOLUTION:

    Choice A is the correct answer.

    47.What is the solution set of x2 + 2x 24 = 0?

    F {4, 6} G {3, 8} H {3, 8} J {4, 6}

    SOLUTION:

    The solutions are 6and4. Choice J is the correct answer.

    48.Which is the solution set of x 2? A

    B

    C

    D

    SOLUTION:Because x is greater than or equal to 2, there should be a closed circle at 2, and the line should be shaded to the right of 2. Choice C is the correct answer.

    Factor each polynomial.

    49.x2 9x + 14

    SOLUTION:

    In this trinomial, b = 9 and c = 14, so m + p is negative and mp is positive. Therefore, m and p must both be negative. List the negative factors of 14, and look for the pair of factors and identify the factors with a sum of 9.

    The correct factors are 2 and 7.

    Factors of 14 Sum 1, 14 15 2, 7 9

    50.n2 8n + 15

    SOLUTION:

    In this trinomial, b = 8 and c = 15, so m + p is negative and mp is positive. Therefore, m and p must both be negative. List the negative factors of 15, and look for the pair of factors and identify the factors with a sum of 8.

    The correct factors are 3 and 5.

    Factors of 15 Sum 1, 15 16 3, 5 8

    51.x2 5x 24

    SOLUTION:

    In this trinomial, b = 5 and c = 24, so m + p is negative and mp is negative. Therefore, m and p must be opposite signs. List the factors of 24, and look for the pair of factors and identify the factors with a sum of 5.

    The correct factors are 3 and 8.

    Factors of 24 Sum 1, 24 23 1, 24 23 2, 12 10 2, 12 10 3, 8 5 3, 8 5 4, 6 2 4, 6 2

    52.z2 + 15z + 36

    SOLUTION:

    In this trinomial, b = 15 and c = 36, so m + p is negative and mp is positive. Therefore, m and p must both be positive.List the factors of 36, and look for the pair of factors and identify the factors with a sum of 15.

    The correct factors are 3 and 12.

    Factors of 36 Sum 1, 36 37 2, 18 20 3, 12 15 4, 9 13 6, 6 12

    53.r2 + 3r 40

    SOLUTION:

    In this trinomial, b = 3 and c = 40, so m + p is positive and mp is negative. Therefore, m and p must be opposite signs. List the factors of 40, and look for the pair of factors and identify the factors with a sum of 3.

    The correct factors are 5 and 8.

    Factors of 40 Sum 1, 40 39 1, 40 39 2, 20 18 2, 20 18 4, 10 6 4, 10 6 5, 8 3 5, 8 3

    54.v2 + 16v + 63

    SOLUTION:

    In this trinomial, b = 16 and c = 63, so m + p is positive and mp is positive. Therefore, m and p must be opposite signs. List the factors of 63, and look for the pair of factors and identify the factors with a sum of 16.

    The correct factors are 7 and 9.

    Factors of 63 Sum 1, 63 64 3, 21 24 7, 9 16

    Solve each equation. Check your solutions.

    55.a(a 9) = 0

    SOLUTION:

    The roots are 0 and 9. Check by substituting 0 and 9 in for a in the original equation.

    and

    The solutions are 0 and 9.

    56.(2y + 6)(y 1) = 0

    SOLUTION:

    The roots are 3 and 1. Check by substituting 3 and 1 in for y in the original equation.

    and

    The solutions are 3 and 1.

    57.10x2 20x = 0

    SOLUTION:

    The roots are 0 and 2. Check by substituting 0 and 2 in for x in the original equation.

    and

    The solutions are 0 and 2.

    58.8b2 12b = 0

    SOLUTION:

    The roots are 0 and . Check by substituting 0 and inforb in the original equation.

    and

    The solutions are 0 and .

    59.15a2 = 60a

    SOLUTION:

    The roots are 0 and 4. Check by substituting 0 and 4 in for a in the original equation.

    and

    The solutions are 0 and 4.

    60.33x2 = 22x

    SOLUTION:

    The roots are 0 and . Check by substituting 0 and inforx in the original equation.

    and

    The solutions are 0 and .

    61.ART A painter has 32 units of yellow dye and 54 units of blue dye to make two shades of green. The units needed to make a gallon of light green and a gallon of dark green are shown. Make a graph showing the numbers of gallons of the two greens she can make, and list three possible solutions.

    SOLUTION:Let x = the number of gallons of light green and let y = the number of gallons of dark green. Then, 4x + y 32andx + 6y 54.Graph4x + y = 32 and x + 6y = 54. Both lines are included in the solution of the system and should be solid.

    Some possible solutions are 2 light, 8 dark; 6 light, 8 dark; 7 light, 4 dark. They fall in the shaded region which represents the solution set.

    Solve each compound inequality. Then graph the solution set.

    62.k + 2 > 12 and k +218

    SOLUTION:

    The solution set is {k |10 < k 16}. To graph the solution set, graph k 16and graph k > 10. Then find the intersection.

    and

    63.d 4 > 3 or d 41

    SOLUTION:

    The solution set is {d|d5ord > 7}. Notice that the graphs do not intersect. To graph the solution set, graph d 5and graph d > 7. Then find the union.

    or

    64.3 < 2x 3 < 15

    SOLUTION:

    The solution set is {x|3 < x < 9}.

    To graph the solution set, graph x < 9 and graph x > 3. Then find the intersection.

    and

    65.3t 75and2t+612

    SOLUTION:

    The solution set is empty. A number cannot be both greater than or equal to 4 and less than or equal to 3.

    and

    66.h 10 < 21 or h + 3 < 2

    SOLUTION:

    The solution set is {h|h < 1}. To graph the solution set, graph h < 1. All numbers less than 1 will also be less than 11.

    or

    67.4 < 2y 2 < 10

    SOLUTION:

    The solution set is {y |3 < y < 6}.

    To graph the solution set, graph y < 6 and graph y > 3. Then find the intersection.

    and

    68.FINANCIALLITERACY A home security company provides security systems for $5 per week, plus an installation fee. The total cost for installation and 12 weeks of service is $210. Write the point-slope form of an equation to find the total fee y for any number of weeks x. What is the installation fee?

    SOLUTION:The slope of the equation of the line that represents the weekly cost is 5. The total cost for 12 weeks of service including installation is $210. So, the line passes through the point (12, 210).

    The point-slope form of an equation to find the total fee y for any number of weeks x is y 210 = 5(x 12). Solve the equation for y to find the flat fee for installation.

    So, the flat fee for installation is $150.

    Find the principal square root of each number.69.16

    SOLUTION:

    70.36

    SOLUTION:

    71.64

    SOLUTION:

    72.81

    SOLUTION:

    73.121

    SOLUTION:

    74.100

    SOLUTION:

    eSolutions Manual - Powered by Cognero Page 1

    8-7 Solving ax^2 + bx + c = 0

  • Factor each polynomial, if possible. If the polynomial cannot be factored using integers, write prime .

    1.3x2 + 17x + 10

    SOLUTION:

    In this trinomial, a = 3, b = 17 and c = 10, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 3(10) or 30 and identify the factors with a sum of 17.

    The correct factors are 2 and 15.

    So, 3x2 + 17x + 10 = (3x + 2) (x +5).

    Factors of 30 Sum 1, 30 31 2, 15 17 5, 6 30

    2.2x2 + 22x + 56

    SOLUTION:

    The GCF of the terms 2x2, 22x, and 56 is 2. Factor this first.

    2x2

    +22x + 56 = 2(x2 + 11x+28)Distributive Property

    In the trinomial, a = 1, b = 11 and c = 28, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 1(28) or 28 and identify the factors with a sum of 11.

    The correct factors are 4 and 7.

    So, 2x2 + 22x + 56= 2(x + 4)(x + 7).

    Factors of 28 Sum 1, 28 29 2, 14 16 4, 7 11

    3.5x2 3x + 4

    SOLUTION:

    In this trinomial, a = 5, b = 3 and c = 4, so m + p is negative and mp is positive. Therefore, m and p must have different signs. List the factors of 5(4) or 20 and identify the factors with a sum of 3.

    There are no factors of 20 with a sum of 3. This trinomial is prime.

    Factors of 20 Sum 1, 20 19 1, 20 19 2, 10 8 2, 10 8 4, 5 1 4, 5 1

    4.3x2 11x 20

    SOLUTION:

    In this trinomial, a = 3, b = 11 and c = 20, so m + p is negative and mp is negative. Therefore, m and p must have different signs. List the factors of 3(20) or 60 and identify the factors with a sum of 11.

    The correct factors are 4 and 15 .

    So, 3x2 11x 20 = (3x +4)(x 5).

    Factors of 60 Sum 1, 60 59 1, 60 59 2, 30 28 2, 30 28 3, 20 17 3, 20 17 4, 15 11 4, 15 11 5, 12 7 5, 12 7 6, 10 4 6, 10 4

    Solve each equation. Confirm your answers using a graphing calculator.

    5.2x2 + 9x + 9 = 0

    SOLUTION:Factor the trinomial.

    Solve the equation using the Zero Product Property. (2x + 3)(x + 3) = 0

    The roots are and3.

    Confirm the roots using a graphing calculator. Let Y1 = 2x2 + 9x + 9 and Y2 = 0. Use the intersect option from the

    CALC menu to find the points intersection.

    Thus, the solutions are and3.

    6.3x2 + 17x + 20 = 0

    SOLUTION:Factor the trinomial.

    Solve the equation using the Zero Product Property. (3x + 5)(x + 4) = 0

    The roots are and4 or about 1.667 and 4.

    Confirm the roots using a graphing calculator. Let Y1 = 3x2 + 17x + 20 and Y2 = 0. Use the intersect option from

    the CALC menu to find the points intersection.

    Thus, the solutions are and4.

    7.3x2 10x + 8 = 0

    SOLUTION:Factor the trinomial.

    Solve the equation using the Zero Product Property.

    The roots are and2orabout1.333and2.

    Confirm the roots using a graphing calculator. Let Y1 = 3x2 10x + 8 and Y2 = 0. Use the intersect option from the

    CALC menu to find the points intersection.

    Thus, the solutions are and2.

    8.2x2 17x + 30 = 0

    SOLUTION:Factor the trinomial.

    Solve the equation using the Zero Product Property. (2x 5) (x 6) = 0

    The roots are and6.

    Confirm the roots using a graphing calculator. Let Y1 = 2x2 17x + 30 and Y2 = 0. Use the intersect option from

    the CALC menu to find the points intersection.

    Thus, the solutions are and6.

    9.CCSSMODELING Ken throws the discus at a school meet.

    a. What is the initial height of the discus? b. After how many seconds does the discus hit the ground?

    SOLUTION:a. The initial height of the discus is for the time t = 0.

    The initial height of the discus is 5 feet. b. When the discus hits the ground, the height will be zero, so h = 0. Substitute 0 for h in the equation and factor the trinomial.

    The solutions to the equation are and . Since time cannot be negative, the discus will hit the ground after or

    2.5 seconds. Check by substituting 2.5 in for x in the original equation.

    Therefore, the discus will hit the ground after 2.5 seconds.

    Factor each polynomial, if possible. If the polynomial cannot be factored using integers, write prime .

    10.5x2 + 34x + 24

    SOLUTION:

    In this trinomial, a = 5, b = 34 and c = 24, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 5(24) or 120 and identify the factors with a sum of 34.

    The correct factors are 4 and 30.

    So, 5x2 + 34x + 24= (5x + 4)(x + 6).

    Factors of 120 Sum 1, 120 121 2, 60 62 3, 40 43 4, 30 34 5, 24 29 6, 20 26 8, 15 23 10, 12 22

    11.2x2 + 19x + 24

    SOLUTION:

    In this trinomial, a = 2, b = 19 and c = 24, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 2(24) or 48 and identify the factors with a sum of 19.

    The correct factors are 3 and 16.

    So, 2x2 + 19x + 24= (2x + 3)(x + 8).

    Factors of 48 Sum 1, 48 49 2, 24 26 3, 16 19 4, 12 16 6, 8 14

    12.4x2 + 22x + 10

    SOLUTION:

    The GCF of the terms 4x2, 22x, and 10 is 2. Factor this first.

    4x2 + 22x + 10 = 2(2x

    2 + 11x+5)Distributive Property

    In the trinomial, a = 2, b = 11 and c = 5, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the factors of 2(5) or 10 and identify the factors with a sum of 11.

    The correct factors are 1 and 10.

    So, 4x2 + 22x + 10= 2(2x + 1)(x + 5).

    Factors of 10 Sum 1, 10 11 2, 5 7

    13.4x2 + 38x + 70

    SOLUTION:

    The GCF of the terms 4x2, 38x, and 70 is 2. Factor this first.

    4x2

    +38x + 70 = 2(2x2 + 19x+35)Distributive Property

    In the trinomial, a = 2, b = 19 and c = 35, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 2(35) or 70 and identify the factors with a sum of 19.

    The correct factors are 5 and 14.

    So, 4x2 + 38x + 70= 2(2x + 5)(x + 7).

    Factors of 70 Sum 1, 70 71 2, 35 37 5, 14 19 7, 10 17

    14.2x2 3x 9

    SOLUTION:

    In this trinomial, a = 2, b = 3 and c = 9, so m + p is negative and mp is negative. Therefore, m and p must have different signs. List the factors of 2(9) or 18 and identify the factors with a sum of 3.

    The correct factors are 3 and 6.

    So, 2x2 3x 9= (2x + 3)(x 3).

    Factors of 18 Sum 1, 18 17 1, 18 17 2, 9 7 2, 9 7 3, 6 3 3, 6 3

    15.4x2 13x + 10

    SOLUTION:

    In this trinomial, a = 4, b = 13 and c = 10, so m + p is negative and mp is positive. Therefore, m and p must both be negative. List the negative factors of 4(10) or 40 and identify the factors with a sum of 13.

    The correct factors are 5 and 8.

    So, 4x2 13x + 10= (4x 5)(x 2).

    Factors of 40 Sum 1, 40 41 2, 20 22 4, 10 14 5, 8 13

    16.2x2 + 3x + 6

    SOLUTION:

    In this trinomial, a = 2, b = 3, and c = 6, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 2(6) or 12 and identify the factors with a sum of 3.

    There are no factors of 12 with a sum of 3.

    So, 2x2 + 3x + 6 is prime.

    Factors of 12 Sum 1, 12 13 2, 6 8 3, 4 7

    17.5x2 + 3x + 4

    SOLUTION:

    In this trinomial, a = 5, b = 3, and c = 4, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 5(4) or 20 and identify the factors with a sum of 3.

    There are no factors of 20 with a sum of 3.

    So, 5x2 + 3x + 4 is prime.

    Factors of 20 Sum 1, 20 21 2, 10 12 4, 5 9

    18.12x2 + 69x + 45

    SOLUTION:

    The GCF of the terms 122x2, 69x, and 45 is 3. Factor this first.

    12x2

    +69x + 45 = 3(4x2 + 23x+15)Distributive Property

    In the trinomial, a = 4, b = 23 and c = 15, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 4(15) or 60 and identify the factors with a sum of 23.

    The correct factors are 3 and 20.

    So, 12x2 + 69x + 45= 3(4x + 3)(x + 5).

    Factors of 60 Sum 1, 60 61 2, 30 32 3, 20 23 4, 15 19 5, 12 17 6, 10 60

    19.4x2 5x + 7

    SOLUTION:

    In this trinomial, a = 4, b = 5, and c = 7, so m + p is negative and mp is positive. Therefore, m and p must both be negative. List the negative factors of 4(7) or 28 and identify the factors with a sum of 5.

    There are no factors of 28 with a sum of 11.

    So, 4x2 5x + 7 is prime.

    Factors of 28 Sum 1,28 29 2, 14 16 4, 7 11

    20.5x2 + 23x + 24

    SOLUTION:

    In this trinomial, a = 5, b = 23 and c = 24, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 5(24) or 120 and identify the factors with a sum of 23.

    The correct factors are 8 and 15.

    So, 5x2 + 23x + 24= (5x + 8)(x + 3).

    Factors of 120 Sum 1, 120 121 2, 60 62 3, 40 43 4, 30 34 5, 24 29 6, 20 26 8, 15 23 10, 12 22

    21.3x2 8x + 15

    SOLUTION:

    In this trinomial, a = 3, b = 8, and c = 15, so m + p is negative and mp is positive. Therefore, m and p must both be negative. List the factors of 3(15) or 45 and identify the factors with a sum of 8.

    There are no factors of 45 with a sum of 8.

    So, 3x2 8x + 15 is prime.

    Factors of 45 Sum 1,45 46 3, 15 18 5, 9 14

    22.SHOTPUT An athlete throws a shot put with an initial upward velocity of 29 feet per second and from an initial height of 6 feet. a. Write an equation that models the height of the shot put in feet with respect to time in seconds. b. After how many seconds will the shot put hit the ground?

    SOLUTION:

    a. A model for the vertical motion of a projected object is given by h = 16t2 + vt + h0, where h is the height in feet,

    t is the time in seconds, v is the initial velocity in feet per second, and h0 is the initial height in feet. The initial velocity

    of the shot put, v, is 29 feet per second. The initial height of the shot put, h0, is 6 feet.

    So, the equation h = 16t2 + 29t + 6 models the height of the shot put in feet with respect to the time in seconds. b. When the shot put hits the ground, the height will be zero, so h = 0.

    The roots are and 2. Because time cannot be negative, the shot put will hit the ground after 2 seconds.

    Solve each equation. Confirm your answers using a graphing calculator.

    23.2x2 + 9x 18 = 0

    SOLUTION:Factor the trinomial.

    The roots are and6.

    Confirm the roots using a graphing calculator. Let Y1 = 2x2 +9x 18 and Y2 = 0. Use the intersect option from the

    CALC menu to find the points intersection.

    Thus, the solutions are and6.

    24.4x2 + 17x + 15 = 0

    SOLUTION:Factor the trinomial then solve the equation using the Zero Product Property. .

    The roots are and3.

    Confirm the roots using a graphing calculator. Let Y1 = 4x2 +17x + 15 and Y2 = 0. Use the intersect option from

    the CALC menu to find the points intersection.

    Thus, the solutions are and3.

    25.3x2 + 26x = 16

    SOLUTION:Factor the trinomial, then solve the equation using the Zero Product Property.

    The roots are and8.

    Confirm the roots using a graphing calculator. Let Y1 = -3x2 +26x and Y2 = 16. Use the intersect option from the

    CALC menu to find the points intersection.

    Thus, the solutions are and8.

    26.2x2 + 13x = 15

    SOLUTION:Factor the trinomial, then solve the equation using the Zero Product Property.

    The roots are and5.

    Confirmtherootsusingagraphingcalculator.LetY1 = -2x2 +13x and Y2 = 15. Use the intersect option from the CALC menu to find the points intersection.

    Thus, the solutions are and5.

    27.3x2 + 5x = 2

    SOLUTION:Factor the trinomial, then solve the equation using the Zero Product Property.

    The roots are and2.

    Confirm the roots using a graphing calculator. Let Y1 = -3x2 +5x and Y2 = -2. Use the intersect option from the

    CALC menu to find the points intersection.

    Thus, the solutions are and2.

    28.4x2 + 19x = 30

    SOLUTION:Factor the trinomial, then solve the equation using the Zero Product Property.

    The roots are and6.

    Confirm the roots using a graphing calculator. Let Y1 = -4x2 +19x and Y2 = -30. Use the intersect option from the

    CALC menu to find the points intersection.

    Thus, the solutions are and6.

    29.BASKETBALL When Jerald shoots a free throw, the ball is 6 feet from the floor and has an initial upward velocity of 20 feet per second. The hoop is 10 feet from the floor. a. Use the vertical motion model to determine an equation that models Jeralds free throw. b. How long is the basketball in the air before it reaches the hoop? c. Raymond shoots a free throw that is 5 foot 9 inches from the floor with the same initial upward velocity. Will the ball be in the air more or less time? Explain.

    SOLUTION:

    a. A model for the vertical motion of a projected object is given by h = 16t2 + vt + h0, where h is the height in feet,

    t is the time in seconds, v is the initial velocity in feet per second, and h0 is the initial height in feet. The initial velocity

    of the basketball, v, is 20 feet per second. The initial height of the basketball, h0, is 6 feet. The height of the hoop, h,

    is 10 feet.

    So, the equation 10 = 16t2 + 20t + 6 models Jeralds free throw.

    b.

    The roots are and 1. The basketball takes second to reach a height of 10 feet on its way up. The basketball

    takes 1 second to reach a height of 10 feet on its way down. So, the basketball will be in the air 1 second before it reaches the hoop. c. The ball will be in the air less time because it starts closer to the ground so the shot will not have as far to fall.

    30.DIVING Ben dives from a 36-foot platform. The equation h = 16t2 + 14t + 36 models the dive. How long will it take Ben to reach the water?

    SOLUTION:When Ben reaches the pool, his height, h will be 0.

    The roots are and 2. Because time cannot be negative, Ben will reach the water after 2 seconds.

    31.NUMBERTHEORY Six times the square of a number x plus 11 times the number equals 2. What are possible values of x?

    SOLUTION:

    Let x = a number. Then, 6x2 +11x = 2.

    The possible values of x are 2 or .

    Factor each polynomial, if possible. If the polynomial cannot be factored using integers, write prime .

    32.6x2 23x 20

    SOLUTION:First factor the number 1 out of each term in the polynomial.

    Then factor the trinomial 6x2 + 23x + 20.

    In this trinomial, a = 6, b = 23 and c = 20, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 6(20) or 120 and identify the factors with a sum of 23.

    The correct factors are 8 and 15.

    So, 6x2 23x 20= (2x + 5)(3x + 4).

    Factors of 120 Sum 1, 120 121 2, 60 62 3, 40 43 4, 30 34 5, 24 29 6, 20 26 8, 15 23 10, 12 22

    33.4x2 15x 14

    SOLUTION:First factor the number 1 out of each term in the polynomial.

    4x2 15x 14 = 1(4x2 + 15x + 14)

    Then factor the trinomial 4x2 + 15x + 14.

    In this trinomial, a = 4, b = 15 and c = 14, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 4(14) or 56 and identify the factors with a sum of 15.

    The correct factors are 7 and 8.

    So, 4x2 15x 14 = (x + 2)(4x + 7).

    Factors of 56 Sum 1, 56 57 2, 28 30 4, 14 18 7, 8 115

    34.5x2 + 18x + 8

    SOLUTION:First factor the number 1 out of each term in the polynomial.

    5x2 + 18x + 8 = 1(5x2 18x 8)

    Then factor the trinomial 5x2 18x 8.

    In this trinomial, a = 5, b = 18 and c = 8, so m + p is negative and mp is negative. Therefore, m and p must have different signs. List the factors of 5(8) or 40 and identify the factors with a sum of 18.

    The correct factors are 20 and 2 .

    So, 5x2 + 18x + 8 = (x 4)(5x + 2).

    Factors of 40 Sum 1, 40 39 1, 40 39 2, 20 18 2, 20 18 4, 10 6 4, 10 6 5, 8 3 5, 8 3

    35.6x2 + 31x 35

    SOLUTION:First factor the number 1 out of each term in the polynomial.

    6x2 + 31x 35 = 1(6x2 31x + 35)

    Then factor the trinomial 6x2 31x + 35.

    In this trinomial, a = 6, b = 31 and c = 35, so m + p is negative and mp is positive. Therefore, m and p must both be negative. List the negative factors of 6(35) or 210 and identify the factors with a sum of 31.

    The correct factors are 21 and 10.

    So, 6x2 + 31x 35 = (2x 7)(3x 5).

    Factors of 210 Sum 1, 210 211 2, 105 107 3, 70 73 5, 42 47 6, 35 41 7, 30 37 10, 21 31 14, 15 29

    36.4x2 + 5x 12

    SOLUTION:First factor the number 1 out of each term in the polynomial. 4x2 + 5x 12 = 1(4x2 5x + 12)

    Then factor the trinomial 4x2 5x + 12.

    In this trinomial, a = 4, b = 5 and c = 12, so m + p is negative and mp is positive. Therefore, m and p must both be negative. List the negative factors of 4(12) or 48 and identify the factors with a sum of 5.

    There are no factors of 48 with a sum of 5. So, 4x2 + 5x 12 is prime.

    Factors of 48 Sum 1, 48 49 2, 24 26 3, 16 19 4, 12 16 6, 8 14

    37.12x2 + x + 20

    SOLUTION:First factor the number 1 out of each term in the polynomial.

    12x2 + x + 20 = 1(12x2 x 20)

    Then factor the trinomial 12x2 x 20.

    In this trinomial, a = 12, b = 1 and c = 20, so m + p is negative and mp is negative. Therefore, m and p must have different signs. List the factors of 12(20) or 240 and identify the factors with a sum of 1.

    The correct factors are 16 and 15.

    So, 12x2 + x + 20 = (4x + 5)(3x 4).

    Factors of 240 Sum 1, 240 239 1, 240 239 2, 120 118 2, 120 118 3, 80 77 3, 80 77 4, 60 56 4, 60 56 5, 48 43 5, 48 43 6, 40 34 6, 40 34 8, 30 22 8, 30 22 10, 24 14 10, 24 14 12, 20 8 12, 20 8 15, 16 1 15, 16 1

    38.URBANPLANNING The city has commissioned the building of a rectangular park. The area of the park can be

    expressed as 660x2 + 524x + 85. Factor this expression to find binomials with integer coefficients that represent

    possible dimensions of the park. If x = 8, what is a possible perimeter of the park?

    SOLUTION:

    So, (22x + 5)(30x + 17) represent the possible dimensions of the park.

    Evaluate each dimension when x = 8 to find the possible length and width of the park when x = 8.

    A possible perimeter of the park is 876 units.

    39.MULTIPLEREPRESENTATIONS In this problem, you will explore factoring a special type of polynomial. a.GEOMETRIC Draw a square and label the sides a. Within this square, draw a smaller square that shares a vertex with the first square. Label the sides b. What are the areas of the two squares? b.GEOMETRIC Cut and remove the small square. What is the area of the remaining region? c.ANALYTICAL Draw a diagonal line between the inside corner and outside corner of the figure, and cut along this line to make two congruent pieces. Then rearrange the two pieces to form a rectangle. What are the dimensions? d.ANALYTICAL Write the area of the rectangle as the product of two binomials.

    e.VERBAL Complete this statement: a2 b2 = Why is this statement true?

    SOLUTION:a.

    The area of a square is found using the formula A = s2. So, the area of the larger square is a

    2 and the area of the

    smaller square is b2.

    b.

    To find the area of the remaining region, subtract the area of the smaller square from the area of the larger square.

    So, the area of the remaining region is a2 b

    2.

    c.

    The width is a b and the length is a + b. d.

    e . The figure with area a2 b2 and the rectangle with area (a b)(a + b) have the same area, so a2 b2 = (a b)(a + b).

    40.CCSSCRITIQUE Zachary and Samantha are solving 6x2 x = 12. Is either of them correct? Explain your

    reasoning.

    SOLUTION:Sample answer: By the Zero Product Property, the equation must be set equal to zero before it can be factored. Then each of the factors can be set equal to zero and solved for x.

    So, Samantha is correct.

    41.REASONING A square has an area of 9x2 + 30xy + 25y2 square inches. The dimensions are binomials with positive integer coefficients. What is the perimeter of the square? Explain.

    SOLUTION:

    The area of the square equals 9x2 + 30xy + 25y

    2.

    So, the length of each side of the square is (3x + 5y) inches.

    The perimeter of the square is (12x + 20y) inches.

    42.CHALLENGE Find all values of k so that 2x2 + kx + 12 can be factored as two binomials using integers.

    SOLUTION:The values for k must be the sum of two negative factors or two positive factors of 2(12) or 24.

    Factors of 24 Possible Values for k 1, 24 25

    1, 24 25 2, 12 14

    2, 12 14 3, 8 11

    3, 8 11 4, 6 10

    4, 6 10

    43.WRITING IN MATH What should you consider when solving a quadratic equation that models a real-world situation?

    SOLUTION:Sample answer: A quadratic equation may have zero, one, or two solutions. If there are two solutions, you must consider the context of the situation to determine whether one or both solutions answer the given question. For example: Timecannotbenegative. A solution stating that a person ran 60 miles per hour is unrealistic.

    44.WRITINGINMATH Explain how to determine which values should be chosen for m and p when factoring a

    polynomial of the form ax2 + bx + c.

    SOLUTION:

    Sample answer: If the trinomial factors, then ax2 + bx + c = ax2 + mx + px + c where m and n are two integers thathave a product equal to ac and a sum equal b. For example, given the trinomial 3x

    2 + 14x + 15, a = 3, b = 14, and c = 15. Find two integers such that mp = 3(15) or 45 and m + p =14.Since59=45and5+9=14,thevaluesofthevariables could be m = 5 and p = 9. Check to see if the trinomial factors using these values for m and p .

    45.GRIDDEDRESPONSE Savannah has two sisters. One sister is 8 years older than her, and the other sister is 2 years younger than her. The product of Savannahs sistersages is 56. How old is Savannah?

    SOLUTION:Let s = Savannahs age. Then, s + 8 = the age of her older sister and s 2 = the age of her younger sister.

    The roots are 12 and 6. Savannahs age cannot be negative. So, Savannah is 6 years old.

    46.What is the product of a3b

    5 and a

    5b

    2?

    A a8b

    7

    B a2b

    3

    C a8b

    3

    D a2b

    7

    SOLUTION:

    Choice A is the correct answer.

    47.What is the solution set of x2 + 2x 24 = 0?

    F {4, 6} G {3, 8} H {3, 8} J {4, 6}

    SOLUTION:

    The solutions are 6and4. Choice J is the correct answer.

    48.Which is the solution set of x 2? A

    B

    C

    D

    SOLUTION:Because x is greater than or equal to 2, there should be a closed circle at 2, and the line should be shaded to the right of 2. Choice C is the correct answer.

    Factor each polynomial.

    49.x2 9x + 14

    SOLUTION:

    In this trinomial, b = 9 and c = 14, so m + p is negative and mp is positive. Therefore, m and p must both be negative. List the negative factors of 14, and look for the pair of factors and identify the factors with a sum of 9.

    The correct factors are 2 and 7.

    Factors of 14 Sum 1, 14 15 2, 7 9

    50.n2 8n + 15

    SOLUTION:

    In this trinomial, b = 8 and c = 15, so m + p is negative and mp is positive. Therefore, m and p must both be negative. List the negative factors of 15, and look for the pair of factors and identify the factors with a sum of 8.

    The correct factors are 3 and 5.

    Factors of 15 Sum 1, 15 16 3, 5 8

    51.x2 5x 24

    SOLUTION:

    In this trinomial, b = 5 and c = 24, so m + p is negative and mp is negative. Therefore, m and p must be opposite signs. List the factors of 24, and look for the pair of factors and identify the factors with a sum of 5.

    The correct factors are 3 and 8.

    Factors of 24 Sum 1, 24 23 1, 24 23 2, 12 10 2, 12 10 3, 8 5 3, 8 5 4, 6 2 4, 6 2

    52.z2 + 15z + 36

    SOLUTION:

    In this trinomial, b = 15 and c = 36, so m + p is negative and mp is positive. Therefore, m and p must both be positive.List the factors of 36, and look for the pair of factors and identify the factors with a sum of 15.

    The correct factors are 3 and 12.

    Factors of 36 Sum 1, 36 37 2, 18 20 3, 12 15 4, 9 13 6, 6 12

    53.r2 + 3r 40

    SOLUTION:

    In this trinomial, b = 3 and c = 40, so m + p is positive and mp is negative. Therefore, m and p must be opposite signs. List the factors of 40, and look for the pair of factors and identify the factors with a sum of 3.

    The correct factors are 5 and 8.

    Factors of 40 Sum 1, 40 39 1, 40 39 2, 20 18 2, 20 18 4, 10 6 4, 10 6 5, 8 3 5, 8 3

    54.v2 + 16v + 63

    SOLUTION:

    In this trinomial, b = 16 and c = 63, so m + p is positive and mp is positive. Therefore, m and p must be opposite signs. List the factors of 63, and look for the pair of factors and identify the factors with a sum of 16.

    The correct factors are 7 and 9.

    Factors of 63 Sum 1, 63 64 3, 21 24 7, 9 16

    Solve each equation. Check your solutions.

    55.a(a 9) = 0

    SOLUTION:

    The roots are 0 and 9. Check by substituting 0 and 9 in for a in the original equation.

    and

    The solutions are 0 and 9.

    56.(2y + 6)(y 1) = 0

    SOLUTION:

    The roots are 3 and 1. Check by substituting 3 and 1 in for y in the original equation.

    and

    The solutions are 3 and 1.

    57.10x2 20x = 0

    SOLUTION:

    The roots are 0 and 2. Check by substituting 0 and 2 in for x in the original equation.

    and

    The solutions are 0 and 2.

    58.8b2 12b = 0

    SOLUTION:

    The roots are 0 and . Check by substituting 0 and inforb in the original equation.

    and

    The solutions are 0 and .

    59.15a2 = 60a

    SOLUTION:

    The roots are 0 and 4. Check by substituting 0 and 4 in for a in the original equation.

    and

    The solutions are 0 and 4.

    60.33x2 = 22x

    SOLUTION:

    The roots are 0 and . Check by substituting 0 and inforx in the original equation.

    and

    The solutions are 0 and .

    61.ART A painter has 32 units of yellow dye and 54 units of blue dye to make two shades of green. The units needed to make a gallon of light green and a gallon of dark green are shown. Make a graph showing the numbers of gallons of the two greens she can make, and list three possible solutions.

    SOLUTION:Let x = the number of gallons of light green and let y = the number of gallons of dark green. Then, 4x + y 32andx + 6y 54.Graph4x + y = 32 and x + 6y = 54. Both lines are included in the solution of the system and should be solid.

    Some possible solutions are 2 light, 8 dark; 6 light, 8 dark; 7 light, 4 dark. They fall in the shaded region which represents the solution set.

    Solve each compound inequality. Then graph the solution set.

    62.k + 2 > 12 and k +218

    SOLUTION:

    The solution set is {k |10 < k 16}. To graph the solution set, graph k 16and graph k > 10. Then find the intersection.

    and

    63.d 4 > 3 or d 41

    SOLUTION:

    The solution set is {d|d5ord > 7}. Notice that the graphs do not intersect. To graph the solution set, graph d 5and graph d > 7. Then find the union.

    or

    64.3 < 2x 3 < 15

    SOLUTION:

    The solution set is {x|3 < x < 9}.

    To graph the solution set, graph x < 9 and graph x > 3. Then find the intersection.

    and

    65.3t 75and2t+612

    SOLUTION:

    The solution set is empty. A number cannot be both greater than or equal to 4 and less than or equal to 3.

    and

    66.h 10 < 21 or h + 3 < 2

    SOLUTION:

    The solution set is {h|h < 1}. To graph the solution set, graph h < 1. All numbers less than 1 will also be less than 11.

    or

    67.4 < 2y 2 < 10

    SOLUTION:

    The solution set is {y |3 < y < 6}.

    To graph the solution set, graph y < 6 and graph y > 3. Then find the intersection.

    and

    68.FINANCIALLITERACY A home security company provides security systems for $5 per week, plus an installation fee. The total cost for installation and 12 weeks of service is $210. Write the point-slope form of an equation to find the total fee y for any number of weeks x. What is the installation fee?

    SOLUTION:The slope of the equation of the line that represents the weekly cost is 5. The total cost for 12 weeks of service including installation is $210. So, the line passes through the point (12, 210).

    The point-slope form of an equation to find the total fee y for any number of weeks x is y 210 = 5(x 12). Solve the equation for y to find the flat fee for installation.

    So, the flat fee for installation is $150.

    Find the principal square root of each number.69.16

    SOLUTION:

    70.36

    SOLUTION:

    71.64

    SOLUTION:

    72.81

    SOLUTION:

    73.121

    SOLUTION:

    74.100

    SOLUTION:

    eSolutions Manual - Powered by Cognero Page 2

    8-7 Solving ax^2 + bx + c = 0

  • Factor each polynomial, if possible. If the polynomial cannot be factored using integers, write prime .

    1.3x2 + 17x + 10

    SOLUTION:

    In this trinomial, a = 3, b = 17 and c = 10, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 3(10) or 30 and identify the factors with a sum of 17.

    The correct factors are 2 and 15.

    So, 3x2 + 17x + 10 = (3x + 2) (x +5).

    Factors of 30 Sum 1, 30 31 2, 15 17 5, 6 30

    2.2x2 + 22x + 56

    SOLUTION:

    The GCF of the terms 2x2, 22x, and 56 is 2. Factor this first.

    2x2

    +22x + 56 = 2(x2 + 11x+28)Distributive Property

    In the trinomial, a = 1, b = 11 and c = 28, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 1(28) or 28 and identify the factors with a sum of 11.

    The correct factors are 4 and 7.

    So, 2x2 + 22x + 56= 2(x + 4)(x + 7).

    Factors of 28 Sum 1, 28 29 2, 14 16 4, 7 11

    3.5x2 3x + 4

    SOLUTION:

    In this trinomial, a = 5, b = 3 and c = 4, so m + p is negative and mp is positive. Therefore, m and p must have different signs. List the factors of 5(4) or 20 and identify the factors with a sum of 3.

    There are no factors of 20 with a sum of 3. This trinomial is prime.

    Factors of 20 Sum 1, 20 19 1, 20 19 2, 10 8 2, 10 8 4, 5 1 4, 5 1

    4.3x2 11x 20

    SOLUTION:

    In this trinomial, a = 3, b = 11 and c = 20, so m + p is negative and mp is negative. Therefore, m and p must have different signs. List the factors of 3(20) or 60 and identify the factors with a sum of 11.

    The correct factors are 4 and 15 .

    So, 3x2 11x 20 = (3x +4)(x 5).

    Factors of 60 Sum 1, 60 59 1, 60 59 2, 30 28 2, 30 28 3, 20 17 3, 20 17 4, 15 11 4, 15 11 5, 12 7 5, 12 7 6, 10 4 6, 10 4

    Solve each equation. Confirm your answers using a graphing calculator.

    5.2x2 + 9x + 9 = 0

    SOLUTION:Factor the trinomial.

    Solve the equation using the Zero Product Property. (2x + 3)(x + 3) = 0

    The roots are and3.

    Confirm the roots using a graphing calculator. Let Y1 = 2x2 + 9x + 9 and Y2 = 0. Use the intersect option from the

    CALC menu to find the points intersection.

    Thus, the solutions are and3.

    6.3x2 + 17x + 20 = 0

    SOLUTION:Factor the trinomial.

    Solve the equation using the Zero Product Property. (3x + 5)(x + 4) = 0

    The roots are and4 or about 1.667 and 4.

    Confirm the roots using a graphing calculator. Let Y1 = 3x2 + 17x + 20 and Y2 = 0. Use the intersect option from

    the CALC menu to find the points intersection.

    Thus, the solutions are and4.

    7.3x2 10x + 8 = 0

    SOLUTION:Factor the trinomial.

    Solve the equation using the Zero Product Property.

    The roots are and2orabout1.333and2.

    Confirm the roots using a graphing calculator. Let Y1 = 3x2 10x + 8 and Y2 = 0. Use the intersect option from the

    CALC menu to find the points intersection.

    Thus, the solutions are and2.

    8.2x2 17x + 30 = 0

    SOLUTION:Factor the trinomial.

    Solve the equation using the Zero Product Property. (2x 5) (x 6) = 0

    The roots are and6.

    Confirm the roots using a graphing calculator. Let Y1 = 2x2 17x + 30 and Y2 = 0. Use the intersect option from

    the CALC menu to find the points intersection.

    Thus, the solutions are and6.

    9.CCSSMODELING Ken throws the discus at a school meet.

    a. What is the initial height of the discus? b. After how many seconds does the discus hit the ground?

    SOLUTION:a. The initial height of the discus is for the time t = 0.

    The initial height of the discus is 5 feet. b. When the discus hits the ground, the height will be zero, so h = 0. Substitute 0 for h in the equation and factor the trinomial.

    The solutions to the equation are and . Since time cannot be negative, the discus will hit the ground after or

    2.5 seconds. Check by substituting 2.5 in for x in the original equation.

    Therefore, the discus will hit the ground after 2.5 seconds.

    Factor each polynomial, if possible. If the polynomial cannot be factored using integers, write prime .

    10.5x2 + 34x + 24

    SOLUTION:

    In this trinomial, a = 5, b = 34 and c = 24, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 5(24) or 120 and identify the factors with a sum of 34.

    The correct factors are 4 and 30.

    So, 5x2 + 34x + 24= (5x + 4)(x + 6).

    Factors of 120 Sum 1, 120 121 2, 60 62 3, 40 43 4, 30 34 5, 24 29 6, 20 26 8, 15 23 10, 12 22

    11.2x2 + 19x + 24

    SOLUTION:

    In this trinomial, a = 2, b = 19 and c = 24, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 2(24) or 48 and identify the factors with a sum of 19.

    The correct factors are 3 and 16.

    So, 2x2 + 19x + 24= (2x + 3)(x + 8).

    Factors of 48 Sum 1, 48 49 2, 24 26 3, 16 19 4, 12 16 6, 8 14

    12.4x2 + 22x + 10

    SOLUTION:

    The GCF of the terms 4x2, 22x, and 10 is 2. Factor this first.

    4x2 + 22x + 10 = 2(2x

    2 + 11x+5)Distributive Property

    In the trinomial, a = 2, b = 11 and c = 5, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the factors of 2(5) or 10 and identify the factors with a sum of 11.

    The correct factors are 1 and 10.

    So, 4x2 + 22x + 10= 2(2x + 1)(x + 5).

    Factors of 10 Sum 1, 10 11 2, 5 7

    13.4x2 + 38x + 70

    SOLUTION:

    The GCF of the terms 4x2, 38x, and 70 is 2. Factor this first.

    4x2

    +38x + 70 = 2(2x2 + 19x+35)Distributive Property

    In the trinomial, a = 2, b = 19 and c = 35, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 2(35) or 70 and identify the factors with a sum of 19.

    The correct factors are 5 and 14.

    So, 4x2 + 38x + 70= 2(2x + 5)(x + 7).

    Factors of 70 Sum 1, 70 71 2, 35 37 5, 14 19 7, 10 17

    14.2x2 3x 9

    SOLUTION:

    In this trinomial, a = 2, b = 3 and c = 9, so m + p is negative and mp is negative. Therefore, m and p must have different signs. List the factors of 2(9) or 18 and identify the factors with a sum of 3.

    The correct factors are 3 and 6.

    So, 2x2 3x 9= (2x + 3)(x 3).

    Factors of 18 Sum 1, 18 17 1, 18 17 2, 9 7 2, 9 7 3, 6 3 3, 6 3

    15.4x2 13x + 10

    SOLUTION:

    In this trinomial, a = 4, b = 13 and c = 10, so m + p is negative and mp is positive. Therefore, m and p must both be negative. List the negative factors of 4(10) or 40 and identify the factors with a sum of 13.

    The correct factors are 5 and 8.

    So, 4x2 13x + 10= (4x 5)(x 2).

    Factors of 40 Sum 1, 40 41 2, 20 22 4, 10 14 5, 8 13

    16.2x2 + 3x + 6

    SOLUTION:

    In this trinomial, a = 2, b = 3, and c = 6, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 2(6) or 12 and identify the factors with a sum of 3.

    There are no factors of 12 with a sum of 3.

    So, 2x2 + 3x + 6 is prime.

    Factors of 12 Sum 1, 12 13 2, 6 8 3, 4 7

    17.5x2 + 3x + 4

    SOLUTION:

    In this trinomial, a = 5, b = 3, and c = 4, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 5(4) or 20 and identify the factors with a sum of 3.

    There are no factors of 20 with a sum of 3.

    So, 5x2 + 3x + 4 is prime.

    Factors of 20 Sum 1, 20 21 2, 10 12 4, 5 9

    18.12x2 + 69x + 45

    SOLUTION:

    The GCF of the terms 122x2, 69x, and 45 is 3. Factor this first.

    12x2

    +69x + 45 = 3(4x2 + 23x+15)Distributive Property

    In the trinomial, a = 4, b = 23 and c = 15, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 4(15) or 60 and identify the factors with a sum of 23.

    The correct factors are 3 and 20.

    So, 12x2 + 69x + 45= 3(4x + 3)(x + 5).

    Factors of 60 Sum 1, 60 61 2, 30 32 3, 20 23 4, 15 19 5, 12 17 6, 10 60

    19.4x2 5x + 7

    SOLUTION:

    In this trinomial, a = 4, b = 5, and c = 7, so m + p is negative and mp is positive. Therefore, m and p must both be negative. List the negative factors of 4(7) or 28 and identify the factors with a sum of 5.

    There are no factors of 28 with a sum of 11.

    So, 4x2 5x + 7 is prime.

    Factors of 28 Sum 1,28 29 2, 14 16 4, 7 11

    20.5x2 + 23x + 24

    SOLUTION:

    In this trinomial, a = 5, b = 23 and c = 24, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 5(24) or 120 and identify the factors with a sum of 23.

    The correct factors are 8 and 15.

    So, 5x2 + 23x + 24= (5x + 8)(x + 3).

    Factors of 120 Sum 1, 120 121 2, 60 62 3, 40 43 4, 30 34 5, 24 29 6, 20 26 8, 15 23 10, 12 22

    21.3x2 8x + 15

    SOLUTION:

    In this trinomial, a = 3, b = 8, and c = 15, so m + p is negative and mp is positive. Therefore, m and p must both be negative. List the factors of 3(15) or 45 and identify the factors with a sum of 8.

    There are no factors of 45 with a sum of 8.

    So, 3x2 8x + 15 is prime.

    Factors of 45 Sum 1,45 46 3, 15 18 5, 9 14

    22.SHOTPUT An athlete throws a shot put with an initial upward velocity of 29 feet per second and from an initial height of 6 feet. a. Write an equation that models the height of the shot put in feet with respect to time in seconds. b. After how many seconds will the shot put hit the ground?

    SOLUTION:

    a. A model for the vertical motion of a projected object is given by h = 16t2 + vt + h0, where h is the height in feet,

    t is the time in seconds, v is the initial velocity in feet per second, and h0 is the initial height in feet. The initial velocity

    of the shot put, v, is 29 feet per second. The initial height of the shot put, h0, is 6 feet.

    So, the equation h = 16t2 + 29t + 6 models the height of the shot put in feet with respect to the time in seconds. b. When the shot put hits the ground, the height will be zero, so h = 0.

    The roots are and 2. Because time cannot be negative, the shot put will hit the ground after 2 seconds.

    Solve each equation. Confirm your answers using a graphing calculator.

    23.2x2 + 9x 18 = 0

    SOLUTION:Factor the trinomial.

    The roots are and6.

    Confirm the roots using a graphing calculator. Let Y1 = 2x2 +9x 18 and Y2 = 0. Use the intersect option from the

    CALC menu to find the points intersection.

    Thus, the solutions are and6.

    24.4x2 + 17x + 15 = 0

    SOLUTION:Factor the trinomial then solve the equation using the Zero Product Property. .

    The roots are and3.

    Confirm the roots using a graphing calculator. Let Y1 = 4x2 +17x + 15 and Y2 = 0. Use the intersect option from

    the CALC menu to find the points intersection.

    Thus, the solutions are and3.

    25.3x2 + 26x = 16

    SOLUTION:Factor the trinomial, then solve the equation using the Zero Product Property.

    The roots are and8.

    Confirm the roots using a graphing calculator. Let Y1 = -3x2 +26x and Y2 = 16. Use the intersect option from the

    CALC menu to find the points intersection.

    Thus, the solutions are and8.

    26.2x2 + 13x = 15

    SOLUTION:Factor the trinomial, then solve the equation using the Zero Product Property.

    The roots are and5.

    Confirmtherootsusingagraphingcalculator.LetY1 = -2x2 +13x and Y2 = 15. Use the intersect option from the CALC menu to find the points intersection.

    Thus, the solutions are and5.

    27.3x2 + 5x = 2

    SOLUTION:Factor the trinomial, then solve the equation using the Zero Product Property.

    The roots are and2.

    Confirm the roots using a graphing calculator. Let Y1 = -3x2 +5x and Y2 = -2. Use the intersect option from the

    CALC menu to find the points intersection.

    Thus, the solutions are and2.

    28.4x2 + 19x = 30

    SOLUTION:Factor the trinomial, then solve the equation using the Zero Product Property.

    The roots are and6.

    Confirm the roots using a graphing calculator. Let Y1 = -4x2 +19x and Y2 = -30. Use the intersect option from the

    CALC menu to find the points intersection.

    Thus, the solutions are and6.

    29.BASKETBALL When Jerald shoots a free throw, the ball is 6 feet from the floor and has an initial upward velocity of 20 feet per second. The hoop is 10 feet from the floor. a. Use the vertical motion model to determine an equation that models Jeralds free throw. b. How long is the basketball in the air before it reaches the hoop? c. Raymond shoots a free throw that is 5 foot 9 inches from the floor with the same initial upward velocity. Will the ball be in the air more or less time? Explain.

    SOLUTION:

    a. A model for the vertical motion of a projected object is given by h = 16t2 + vt + h0, where h is the height in feet,

    t is the time in seconds, v is the initial velocity in feet per second, and h0 is the initial height in feet. The initial velocity

    of the basketball, v, is 20 feet per second. The initial height of the basketball, h0, is 6 feet. The height of the hoop, h,

    is 10 feet.

    So, the equation 10 = 16t2 + 20t + 6 models Jeralds free throw.

    b.

    The roots are and 1. The basketball takes second to reach a height of 10 feet on its way up. The basketball

    takes 1 second to reach a height of 10 feet on its way down. So, the basketball will be in the air 1 second before it reaches the hoop. c. The ball will be in the air less time because it starts closer to the ground so the shot will not have as far to fall.

    30.DIVING Ben dives from a 36-foot platform. The equation h = 16t2 + 14t + 36 models the dive. How long will it take Ben to reach the water?

    SOLUTION:When Ben reaches the pool, his height, h will be 0.

    The roots are and 2. Because time cannot be negative, Ben will reach the water after 2 seconds.

    31.NUMBERTHEORY Six times the square of a number x plus 11 times the number equals 2. What are possible values of x?

    SOLUTION:

    Let x = a number. Then, 6x2 +11x = 2.

    The possible values of x are 2 or .

    Factor each polynomial, if possible. If the polynomial cannot be factored using integers, write prime .

    32.6x2 23x 20

    SOLUTION:First factor the number 1 out of each term in the polynomial.

    Then factor the trinomial 6x2 + 23x + 20.

    In this trinomial, a = 6, b = 23 and c = 20, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 6(20) or 120 and identify the factors with a sum of 23.

    The correct factors are 8 and 15.

    So, 6x2 23x 20= (2x + 5)(3x + 4).

    Factors of 120 Sum 1, 120 121 2, 60 62 3, 40 43 4, 30 34 5, 24 29 6, 20 26 8, 15 23 10, 12 22

    33.4x2 15x 14

    SOLUTION:First factor the number 1 out of each term in the polynomial.

    4x2 15x 14 = 1(4x2 + 15x + 14)

    Then factor the trinomial 4x2 + 15x + 14.

    In this trinomial, a = 4, b = 15 and c = 14, so m + p is positive and mp is positive. Therefore, m and p must both be positive. List the positive factors of 4(14) or 56 and identify the factors with a sum of 15.

    The correct factors are 7 and 8.

    So, 4x2 15x 14 = (x + 2)(4x + 7).

    Factors of 56 Sum 1, 56 57 2, 28 30 4, 14 18 7, 8 115

    34.5x2 + 18x + 8

    SOLUTION:First factor the number 1 out of each term in the polynomial.

    5x2 + 18x + 8 = 1(5x2 18x 8)

    Then factor the trinomial 5x2 18x 8.

    In this trinomial, a = 5, b = 18 and c = 8, so m + p is negative and mp is negative. Therefore, m and p must have different signs. List the factors of 5(8) or 40 and identify the factors with a sum of 18.

    The correct factors are 20 and 2 .

    So, 5x2 + 18x + 8 = (x 4)(5x + 2).

    Factors of 40 Sum 1, 40 39 1, 40 39 2, 20 18 2, 20 18 4, 10 6 4, 10 6 5, 8 3 5, 8 3

    35.6x2 + 31x 35

    SOLUTION:First factor the number 1 out of each term in the polynomial.

    6x2 + 31x 35 = 1(6x2 31x + 35)

    Then factor the trinomial 6x2 31x + 35.

    In this trinomial, a = 6, b = 31 and c = 35, so m + p is negative and mp is positive. Therefore, m and p must both be negative. List the negative factors of 6(35) or 210 and identify the factors with a sum of 31.

    The correct factors are 21 and 10.

    So, 6x2 + 31x 35 = (2x 7)(3x 5).

    Factors of 210 Sum 1, 210 211 2, 105 107 3, 70 73 5, 42 47 6, 35 41 7, 30 37 10, 21 31 14, 15 29

    36.4x2 + 5x 12

    SOLUTION:First factor the number 1 out of each term in the polynomial. 4x2 + 5x 12 = 1(4x2 5x + 12)

    Then factor the trinomial 4x2 5x + 12.

    In this trinomial, a = 4, b = 5 and c = 12, so m + p is negative and mp is positive. Therefore, m and p must both be negative. List the negative factors of 4(12) or 48 and identify the factors with a sum of 5.

    There are no factors of 48 with a sum of 5. So, 4x2 + 5x 12 is prime.

    Factors of 48 Sum 1, 48 49 2, 24 26 3, 16 19 4, 12 16 6, 8 14

    37.12x2 + x + 20

    SOLUTION:First factor the number 1 out of each term in the polynomial.

    12x2 + x + 20 = 1(12x2 x 20)

    Then factor the trinomial 12x2 x 20.

    In this trinomial, a = 12, b = 1 and c = 20, so m + p is negative and mp is negative. Therefore, m and p must have different signs. List the factors of 12(20) or 240 and identify the factors with a sum of 1.

    The correct factors are 16 and 15.

    So, 12x2 + x + 20 = (4x + 5)(3x 4).

    Factors of 240 Sum 1, 240 239 1, 240 239 2, 120 118 2, 120 118 3, 80 77 3, 80 77 4, 60 56 4, 60 56 5, 48 43 5, 48 43 6, 40 34 6, 40 34 8, 30 22 8, 30 22 10, 24 14 10, 24 14 12, 20 8 12, 20 8 15, 16 1 15, 16 1

    38.URBANPLANNING The city has commissioned the building of a rectangular park. The area of the park can be

    expressed as 660x2 + 524x + 85. Factor this expression to find binomials with integer coefficients that represent

    possible dimensions of the park. If x = 8, what is a possible perimeter of the park?

    SOLUTION:

    So, (22x + 5)(30x + 17) represent the possible dimensions of the park.

    Evaluate each dimension when x = 8 to find the possible length and width of the park when x = 8.

    A possible perimeter of the park is 876 units.

    39.MULTIPLEREPRESENTATIONS In this problem, you will explore factoring a special type of polynomial. a.GEOMETRIC Draw a square and label the sides a. Within this square, draw a smaller square that shares a vertex with the first square. Label the sides b. What are the areas of the two squares? b.GEOMETRIC Cut and remove the small square. What is the area of the remaining region? c.ANALYTICAL Draw a diagonal line between the inside corner and outside corner of the figure, and cut along this line to make two congruent pieces. Then rearrange the two pieces to form a rectangle. What are the dimensions? d.ANALYTICAL Write the area of the rectangle as the product of two binomials.

    e.VERBAL Complete this statement: a2 b2 = Why is this statement true?

    SOLUTION:a.

    The area of a square is found using the formula A = s2. So, the area of the larger square is a

    2 and the area of the

    smaller square is b2.

    b.

    To find the area of the remaining region, subtract the area of the smaller square from the area of the larger square.

    So, the area of the remaining region is a2 b

    2.

    c.

    The width is a b and the length is a + b. d.

    e . The figure with area a2 b2 and the rectangle with area (a b)(a + b) have the same area, so a2 b2 = (a b)(a + b).

    40.CCSSCRITIQUE Zachary and Samantha are solving 6x2 x = 12. Is either of them correct? Explain your

    reasoning.

    SOLUTION:Sample answer: By the Zero Product Property, the equation must be set equal to zero before it can be factored. Then each of the factors can be set equal to zero and solved for x.

    So, Samantha is correct.

    41.REASONING A square has an area of 9x2 + 30xy + 25y2 square inches. The dimensions are binomials with positive integer coefficients. What is the perimeter of the square? Explain.

    SOLUTION:

    The area of the square equals 9x2 + 30xy + 25y

    2.

    So, the length of each side of the square is (3x + 5y) inches.

    The perimeter of the square is (12x + 20y) inches.

    42.CHALLENGE Find all values of k so that 2x2 + kx + 12 can be factored as two binomials using integers.

    SOLUTION:The values for k must be the sum of two negative factors or two positive factors of 2(12) or 24.

    Factors of 24 Possible Values for k 1, 24 25

    1, 24 25 2, 12 14

    2, 12 14 3, 8 11

    3, 8 11 4, 6 10

    4, 6 10

    43.WRITING IN MATH What should you consider when solving a quadratic equation that models a real-world situation?

    SOLUTION:Sample answer: A quadratic equation may have zero, one, or two solutions. If there are two solutions, you must consider the context of the situation to determine whether one or both solutions answer the given question. For example: Timecannotbenegative. A solution stating that a person ran 60 miles per hour is unrealistic.

    44.WRITINGINMATH Explain how to determine which values should be chosen for m and p when factoring a

    polynomial of the form ax2 + bx + c.

    SOLUTION:

    Sample answer: If the trinomial factors, then ax2 + bx + c = ax2 + mx + px + c where m and n are two integers thathave a product equal to ac and a sum equal b. For example, given the trinomial 3x

    2 + 14x + 15, a = 3, b = 14, and c = 15. Find two integers such that mp = 3(15) or 45 and m + p =14.Since59=45and5+9=14,thevaluesofthevariables could be m = 5 and p = 9. Check to see if the trinomial factors using these values for m and p .

    45.GRIDDEDRESPONSE Savannah has two sisters. One sister is 8 years older than her, and the other sister is 2 years younger than her. The product of Savannahs sistersages is 56. How old is Savannah?

    SOLUTION:Let s = Savannahs age. Then, s + 8 = the age of her older sister and s 2 = the age of her younger sister.

    The roots are 12 and 6. Savannahs age cannot be negative. So, Savannah is 6 years old.

    46.What is the product of a3b

    5 and a

    5b

    2?

    A a8b

    7

    B a2b

    3

    C a8b

    3

    D a2b

    7

    SOLUTION:

    Choice A is the correct answer.

    47.What is the solution set of x2 + 2x 24 = 0?

    F {4, 6} G {3, 8} H {3, 8} J {4, 6}

    SOLUTION:

    The solutions are 6and4. Choice J is the correct answer.

    48.Which is the solution set of x 2? A

    B

    C

    D

    SOLUTION:Because x is greater than or equal to 2, there should be a closed circle at 2, and the line should be shaded to the right of 2. Choice C is the correct answer.

    Factor each polynomial.

    49.x2 9x + 14

    SOLUTION:

    In this trinomial, b = 9 and c = 14, so m + p is negative and mp is positive. Therefore, m and p must both be negative. List the negative factors of 14, and look for the pair of factors and identify the factors with a sum of 9.

    The correct factors are 2 and 7.

    Factors of 14 Sum 1, 14 15 2, 7 9

    50.n2 8n + 15

    SOLUTION:

    In this trinomial, b = 8 and c = 15, so m + p is negative and mp is positive. Therefore, m and p must both be negative. List the negative factors of 15, and look for the pair of factors and identify the factors with a sum of 8.

    The correct factors are 3 and 5.

    Factors of 15 Sum 1, 15 16 3, 5 8

    51.x2 5x 24

    SOLUTION:

    In this trinomial, b = 5 and c = 24, so m + p is negative and mp is negative. Therefore, m and p must be opposite signs. List the factors of 24, and look for the pair of factors and identify the factors with a sum of 5.

    The correct factors are 3 and 8.

    Factors of 24 Sum 1, 24 23 1, 24 23 2, 12 10 2, 12 10 3, 8 5 3, 8 5 4, 6 2 4, 6 2

    52.z2 + 15z + 36

    SOLUTION:

    In this trinomial, b = 15 and c = 36, so m + p is negative and mp is positive. Therefore, m and p must both be positive.List the factors of 36, and look for the pair of factors and identify the factors with a sum of 15.

    The correct factors are 3 and 12.

    Factors of 36 Sum 1, 36 37 2, 18 20 3, 12 15 4, 9 13 6, 6 12

    53.r2 + 3r 40

    SOLUTION:

    In this trinomial, b = 3 and c = 40, so m + p is positive and mp is negative. Therefore, m and p must be opposite signs. List the factors of 40, and look for the pair of factors and identify the factors with a sum of 3.

    The correct factors are 5 and 8.

    Factors of 40 Sum 1, 40 39 1, 40 39 2, 20 18 2, 20 18 4, 10 6 4, 10 6 5, 8 3 5, 8 3

    54.v2 + 16v + 63

    SOLUTION:

    In this trinomial, b = 16 and c = 63, so m + p is positive and mp is positive. Therefore, m and p must be opposite signs. List the factors of 63, and look for the pair of factors and identify the factors with a sum of 16.

    The correct factors are 7 and 9.

    Factors of 63 Sum 1, 63 64 3, 21 24 7, 9 16

    Solve each equation. Check your solutions.

    55.a(a 9) = 0

    SOLUTION:

    The roots are 0 and 9. Check by substituting 0 and 9 in for a in the original equation.

    and

    The solutions are 0 and 9.

    56.(2y + 6)(y 1) = 0

    SOLUTION:

    The roots are 3 and 1. Check by substituting 3 and 1 in for y in the original equation.

    and

    The solutions are 3 and 1.

    57.10x2 20x = 0

    SOLUTION:

    The roots are 0 and 2. Check by substituting 0 and 2 in for x in the original equation.

    and

    The solutions are 0 and 2.

    58.8b2 12b = 0

    SOLUTION:

    The roots are 0 and . Check by substituting 0 and inforb in the original equation.

    and

    The solutions are 0 and .

    59.15a2 = 60a

    SOLUTION:

    The roots are 0 and 4. Check by substituting 0 and 4 in for a in the original equation.

    and

    The solutions are 0 and 4.

    60.33x2 = 22x

    SOLUTION:

    The roots are 0 and . Check by substituting 0 and inforx in the original equation.

    and

    The solutions are 0 and .

    61.ART A painter has 32 units of yellow dye and 54 units of blue dye to make two shades of green. The units needed to make a gallon of light green and a gallon of dark green are shown. Make a graph showing the numbers of gallons of the two greens she can make, and list three possible solutions.

    SOLUTION:Let x = the number of gallons of light green and let y = the number of gallons of dark green. Then, 4x + y 32andx + 6y 54.Graph4x + y = 32 and x + 6y = 54. Both lines are included in the solution of the system and should be solid.

    Some possible solutions are 2 light, 8 dark; 6 light, 8 dark; 7 light, 4 dark. They fall in the shaded region which represents the solution set.

    Solve each compound inequality. Then graph the solution set.

    62.k + 2 > 12 and k +218

    SOLUTION:

    The solution set is {k |10 < k 16}. To graph the solution set, graph k 16and graph k > 10. Then find the intersection.

    and

    63.d 4 > 3 or d 41

    SOLUTION:

    The solution set is {d|d5ord > 7}. Notice that the graphs do not intersect. To graph the solution set, graph d 5and graph d > 7. Then find the union.

    or

    64.3 < 2x 3 < 15

    SOLUTION:

    The solution set is {x|3 < x < 9}.

    To graph the solution set, graph x < 9 and graph x > 3. Then find the intersection.

    and

    65.3t 75and2t+612

    SOLUTION:

    The solution set is empty. A number cannot be both greater than or equal to 4 and less than or equal to 3.

    and

    66.h 10 < 21 or h + 3 < 2

    SOLUTION:

    The solution set is {h|h < 1}. To graph the solution set, graph h < 1. All numbers less than 1 will also be less than 11.

    or

    67.4 < 2y 2 < 10

    SOLUTION:

    The solution set is {y |3 < y < 6}.

    To graph the solution set, graph y < 6 and graph y > 3. Then find the intersection.

    and

    68.FINANCIALLITERACY A home security company provides security systems for $5 per week, plus an installation fee. The total cost for installation and 12 weeks of service is $210. Write the point-slope form of an equation to find the total fee y for any number of weeks x. What is the installation fee?

    SOLUTION:The slope of the equation of the line that represents the weekly cost is 5. The total cost for 12 weeks of service including installation is $210. So, the line passes through the point (12, 210).

    The point-slope form of an equation to find the total fee y for any number of weeks x is y 210 = 5(x 12). Solve the equation for y to find the flat fee for installation.

    So, the flat fee for installation is $150.

    Find the principal square root of each number.69.16

    SOLUTION:

    70.36

    SOLUTIO


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