# Are the graph y=-3x+7 and  y=-3x+2 perpendicular?

Mar 29, 2018

No.

#### Explanation:

The formula for the slopes of perpendicular lines is

${m}_{1} \cdot {m}_{2} = - 1$

That means that the first gradient times the second gradient should equal $- 1$. In this question

$- 3 \cdot \left(- 3\right) = 9$

so they are not perpendicular.