CPM Homework Help : GB8I Problem 5-111

What is the equation of the line that has a $y$ -intercept of $(0, –3)$ and passes through the point $(–9, –9)$ ?

Step 1:

Use the two points to find the rise and the run. Then divide the rise by the run. That will give you the slope.

Step 2:

Substitute the slope for $m$ in the equation below. Then substitute the $y$ -coordinate of the $y$ -intercept for $b$ .
$y = mx + b$

Answer:

$y = \frac { 2 } { 3 } x - 3$

Complete the table in the eTool below to determine the equation of the line.
Click the link at right for the full version of the eTool: 5-111 HW eTool