Warm-Up Exercises

1. Graph y = –x – 2 with domain –2, –1, 0, 1, and 2.

ANSWER

Warm-Up Exercises

2. 3x + 4y = 16

Rewrite the equation so y is a function of x.

ANSWER 34

y = – x + 4

3. –6x – 2y = –12

ANSWER y = –3x + 6

Warm-Up Exercises

Simplify.

Write original equation.

Standardized Test PracticeEXAMPLE 1

Test (1, –4): 3x – y = 7

3(1) – (–4) = ?

7 Substitute 1 for x and –4 for y.

So, (3, 4) is not a solution, but (1, – 4) is a solution of 3x – y = 7.

ANSWER

The correct answer is B. A B DC

7 = 7

Warm-Up Exercises

SOLUTION

STEP 1Make a table.

x 0 2 4 6 8

y 4 3 2 1 0

EXAMPLE 4 Graph a linear function

12Graph the function y = with domain x 0. – x + 4

Then identify the range of the function.

Warm-Up Exercises

STEP 2

STEP 3

Connect the points with a ray because the domain is restricted.

STEP 4

Identify the range. From the graph, you can see that all points have a y-coordinate of 4 or less, so the range of the function is y ≤ 4.

EXAMPLE 4 Graph a linear function

Plot the points.

Warm-Up ExercisesDaily Homework Quiz

1. Graph y + 2x = 4.

ANSWER

Warm-Up Exercises

Warm-up: #18 and #19 need to be completed by the end of the warm up. You will have 15 minutes. Your work for the benchmark will be collected today.

Homework: Page 157 #3-8 all, #11-25 all

Warm-Up Exercises

Substitute 3 for x and 4 for y.

Simplify.

Write original equation.

Check whether each ordered pair is a solution of the equation.

SOLUTION

Which ordered pair is a solution of 3x – y = 7?

EXAMPLE 1 Standardized Test Practice

(3, 4)A (1, –4)B (5, –3)C (–1, –2)D

Test (3, 4):

3(3) – 4 =? 7

3x – y = 7

5 = 7

Warm-Up ExercisesExample 2

Tell whether 4, – is a solution of x + 2y = 5.12

not a solutionANSWER

Warm-Up Exercises

Solve the equation for y.

SOLUTION

Example 3 Graph an equation

Graph the equation –2x + y = –3.

–2x + y = –3y = 2x –3

STEP 1

Warm-Up ExercisesGraph an equationExample 3

Plot the points. Notice that the points appear to lie on a line.

STEP 3

Make a table by choosing a few values for x and finding the values of y.

x –2 –1 0 1 2

y –7 –5 –3 –1 1

STEP 2

Warm-Up ExercisesGraph an equationEXAMPLE 3

Connect the points by drawing a line through them. Use arrows to indicate that the graph goes on without end.

STEP 4

Warm-Up ExercisesExample 4

Graph the equation.

y + 3x = –2

ANSWER

Warm-Up Exercises

Graph y = 2.

Graph y = b and x = aEXAMPLE 5

SOLUTION

For every value of x, the value of y is 2. The graph of the equation y = 2 is a horizontal line 2 units above the x-axis.

Warm-Up Exercises

Example 6) Graph x = –1

Warm-Up ExercisesGUIDED PRACTICE

7. y = 2.5

Graph the equation.

ANSWER

Warm-Up ExercisesGUIDED PRACTICE

8. x = –4

Graph the equation.

ANSWER

Warm-Up Exercises

Warm-Up Exercises

Warm-Up Exercises

Warm-up: Number 18 and 19 need to be completed

Homework: Worksheet given in class AND

Page 157 #26-31 all, and # 35 # 36

Warm-Up Exercises

SOLUTION

RUNNINGThe distance d (in miles) that a runner travels is given by the function d = 6t where t is the time (in hours) spent running. The runner plans to go for a 1.5 hour run. Graph the function and identify its domain and range.

STEP 1Identify whether the problem specifies the domain or the range. You know the amount of time the runner plans to spend running. Because time is the independent variable, the domain is specified in this problem. The domain of the function is 0 ≤ t ≤ 1.5.

Solve a multi-step problemEXAMPLE 1

Warm-Up ExercisesEXAMPLE 1 Solve a multi-step problem

STEP 2Graph the function. Make a table of values. Then plot and connect the points.

t (hours) 0 0.5 1 1.5d (miles) 0 3 6 9

STEP 3Identify the unspecified domain or range. From the table or graph, you can see that the range of the function is 0 ≤ d ≤ 9.

Warm-Up Exercises

SOLUTION

EXAMPLE 2 Solve a related problem

WHAT IF?Suppose the runner in Example 5 instead plans to run 12 miles. Graph the function and identify its domain and range.

STEP 1Identify whether the problem specifies the domain or the range. You are given the distance that the runner plans to travel. Because distance is the dependent variable, the range is specified in this problem. The range of the function is 0 ≤ d ≤ 12.

Warm-Up ExercisesEXAMPLE 2 Solve a related problem

STEP 2Graph the function. To make a table, you can substitute d-values (be sure to include 0 and 12) into the function d = 6t and solve for t.

t (hours) 0 1 2

d (miles) 0 6 12

STEP 3

Identify the unspecified domain or range. From the table or graph, you can see that the domain of the function is 0 ≤ t ≤ 2.

Warm-Up ExercisesExample 3

GAS COSTS

For gas that costs $2 per gallon, the equation C = 2g gives the cost C (in dollars) of pumping g gallons of gas. You plan to pump $10 worth of gas. Graph the function and identify its domain and range.

domain: 0 ≤ g ≤ 5, range: 0 ≤ C ≤ 10

ANSWER

Warm-Up ExercisesExample 4

Graph the function y = –3x + 1 with domain x 0. Then identify the range of the function.

ANSWER y 1

Warm-Up ExercisesExample 5

The distance in miles an elephant walks in t hours is given by d = 5t. The elephant walks for 2.5 hours. Graph the function and identify its domain and range.

domain: 0 t 2.5 range: 0 d 12.5ANSWER

Warm-Up Exercises

26) y ≥ - 227) y ≥ 328) y = 429) y = -630) -5 ≤ y ≤ 331) -4 ≤ y ≤ 0

Warm-Up Exercises

35) Domain: 0 ≤ f ≤5 Range: 0 ≤ w ≤2.2 2 pounds

36) Domain: 0 ≤ t ≤ 4 Range: 0 ≤ d ≤ 200 125 miles