CPM Homework Help : GB8I Problem 7-104

Without graphing, determine which of the following equations represents lines that are parallel to each other. Which are perpendicular? Show how you know.

$–3x + y = 5$

$–5x + y = 3$

$x + 5y = -15$

$-15x + 5y = -25$

Step 1:

Put each equation into slope-intercept form
( $y = mx + b$ , where $m$ is the slope and $b$ is the $y$ -intercept). That means to solve for $y$ .

Step 2:

Compare the slopes.
If they are equal then they are parallel.
If they are the negative reciprocal of each other then they are perpendicular.