# The equation of line AB is (y−3) = 5 (x − 4). What is the slope of a line perpendicular to line AB?

Apr 30, 2017

${m}_{\text{perpendicular}} = - \frac{1}{5}$

#### Explanation:

$y - 3 = 5 \left(x - 4\right) \text{ is in "color(blue)"point-slope form}$

$\text{that is } y - {y}_{1} = m \left(x - {x}_{1}\right)$

$\text{where m represents the slope}$

$\Rightarrow \text{slope } = m = 5$

$\text{the slope of a perpendicular line is the}$
$\textcolor{b l u e}{\text{negative inverse of m}}$

$\Rightarrow {m}_{\text{perpendicular}} = - \frac{1}{5}$