4.3 Graphing Equations of Lines From Intercepts Algebra 4.3 Graphing Equations of Lines From Intercepts

Ax + By = C Standard Form The slope is - A B x coefficient y coefficient constant The slope is - A B

You can graph lines by finding the 2 points where the line crosses the axis lines. These are called the x-intercept and the y-intercept.

The Intercepts y y intercept (x = 0) x intercept (y = 0) x

Find the y intercept and the x intercept for 2x + 3y = 6 At the y intercept, x = 0 2 3 2x + 3(0) = 6 2x = 6 x = 3 At the x intercept, y = 0

2x + 3y = 6 y intercept (0,2) x intercept (3,0) 2(0) + 3y = 6 3y = 6

Graphing from Intercepts STEPS Leave the equation in its original form. Set up an x/y table with 0’s filled in x y y intercept x intercept Compute the y intercept and x intercept values to find the coordinates 4. Plot the 2 points and connect for the line

Now you try one……..

Find the y intercept and the x intercept for 2x - 6y = -18 At the y intercept, x = 0 3 -9 2x - 6(0) = -18 2x = -18 x = -9 At the x intercept, y = 0

. . 2x - 6y = -18 y intercept (0,3) x intercept (-9,0) 2(0) - 6y = -18

Homework P. 222 41-55, 60-63