# What is the slope of a line perpendicular to y=3x+4?

Mar 12, 2018

$- \frac{1}{3}$

#### Explanation:

Lines that are perpendicular to each other always follow the rule:

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

M=3

Therefore plug it in:

$3 \cdot {m}_{2} = - 1$

${m}_{2} = - \frac{1}{3}$

Therefore the slope of the line perpendicular to $y = 3 x + 4$ is

$- \frac{1}{3}$