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 Intercepts

Find 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 1215

182124

255075

100125150175200 f xx

025

2000 -int. Total Distance

-int. Time to Run

the Total

Distance

y

x

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 Intercepts

Use intercepts to graph the line described by the equation.3x – 7y = 21

x

y

yx07

30

Holt Algebra 1

5-2 Using Intercepts

Use intercepts to graph the line described by the equation.

y = –x + 4

x

y

yx04

40

Holt Algebra 1

5-2 Using Intercepts

Use intercepts to graph the line described by the equation.

–3x + 4y = –12

x

y

yx04

30

Holt Algebra 1

5-2 Using Intercepts

Use 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 Intercepts

Warm Up 1. 5x + 0 = –10

Solve 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

1

2

3

3

4

5

1

2

3

3

4

5

2y x