Holt Algebra 1
5-2 Using Intercepts
Students will be able to: Find x- and y-intercepts and interpret their meanings in real-world situations. And also to use x- and y-intercepts to graph lines.
Learning Target
Holt Algebra 1
5-2 Using Intercepts
The y-intercept is the y-coordinate of the point where the graph intersects the y-axis. The x-coordinate of this point is always 0.
The x-intercept is the x-coordinate of the point where the graph intersects the x-axis. The y-coordinate of this point is always 0.
Holt Algebra 1
5-2 Using InterceptsFind the x- and y-intercepts.
2,0 0,1
Holt Algebra 1
5-2 Using Intercepts
5x – 2y = 10Find the x- and y-intercepts.
0, 5 & 2,0
yx02
50
Holt Algebra 1
5-2 Using Intercepts
Find the x- and y-intercepts.
2,0
0,3
Holt Algebra 1
5-2 Using Intercepts
Find the x- and y-intercepts.–3x + 5y = 30
0,6 & 10,0
yx0
1060
Holt Algebra 1
5-2 Using Intercepts
Find the x- and y-intercepts.4x + 2y = 16
0,8 & 4,0
yx04
80
Holt Algebra 1
5-2 Using InterceptsTrish can run the 200 m dash in 25 s. The function f(x) = 200 – 8x gives the distance remaining to be run after x seconds. Graph this function and find the intercepts. What does each intercept represent?
Neither time nor distance can be negative, so choose several nonnegative values for x. Use the function to generate ordered pairs.
f x
x3 6 9 1215182124
255075
100125150175200 f xx
025
2000 -int. Total Distance
-int. Time to Run the Total Distance
yx
Holt Algebra 1
5-2 Using Intercepts
Neither pens nor notebooks can be negative, so choose several nonnegative values for x. Use the function to generate ordered pairs.
The school sells pens for $2.00 and notebooks for $3.00. The equation 2x + 3y = 60 describes the number of pens x and notebooks y that you can buy for $60. Graph the function and find its intercepts.
y
x4 8 121418222630
369
1215182124 yx
030
200
30,0
0,20
Holt Algebra 1
5-2 Using InterceptsUse intercepts to graph the line described by the equation.3x – 7y = 21
x
y
yx07
30
Holt Algebra 1
5-2 Using InterceptsUse intercepts to graph the line described by the equation.
y = –x + 4
x
yyx
04
40
Holt Algebra 1
5-2 Using InterceptsUse intercepts to graph the line described by the equation.
–3x + 4y = –12
x
yyx
04
30
Holt Algebra 1
5-2 Using InterceptsUse intercepts to graph the line described by the equation.
HW pp. 306-308/13-33, 38-42even, 43
x
y
yx06
20
Holt Algebra 1
5-2 Using InterceptsWarm Up 1. 5x + 0 = –10Solve each equation.
–2
11
1
–2
2. 33 = 0 + 3y
3.
4. 2x + 14 = –3x + 4
5. –5y – 1 = 7y + 5
Holt Algebra 1
5-2 Using Intercepts
Express the relation {(1, 3), (2, 4), (3, 5)} as a table, as a graph, and as a mapping diagram.
x yTable
x
yx y
123
345
123
345
2y x
