Standard Form of aLinear Function

Unit 5, Lesson 9

The standard form of a linear equation is:

Definition

CByAx

Definition: X-intercept: the x-coordinate of the point

where a line crosses the x-axis.

To find the x-intercept of a line, substitute 0 for y and solve.

To find the y-intercept of a line, substitute 0 for x and solve.

Find the x- and y-intercepts of 2x + 5y = 6.

Step 1: To find the x-intercept, substitute 0 for y and solve for x.

2x + 5(0) = 6

2x = 6

x = 3

The x-intercept is 3.

Standard Form

Find the x- and y-intercepts of 2x + 5y = 6.

Step 2: To find the y-intercept, substitute 0 for x and solve for y. 2(0) + 5y = 6

5y = 6

y =

The y-intercept is .

6565

Standard Form

Find the x- and y-intercepts of 4x – 9y = –12.

3

4

129

1290

12904

y

y

y

y

3

124

1204

12094

x

x

x

x

3x + 5y = 15

3x + 5(0) = 15

3x = 15

x = 5

3x + 5y = 15

3(0) + 5y = 15

5y = 15

y = 3

Graph the equation 3x + 5y = 15.

GRAPHING in Standard Form

Plot (5, 0) and (0, 3).

Draw a line through the points.

Graph 2x – y = 6 using x- and y-intercepts.

You try:

6

6

60

602

y

y

y

y

3

62

602

x

x

x

http://www.phschool.com/atschool/academy123/english/academy123_content/wl-book-demo/ph-212s.html

Video Example: