# What is the slope of any line perpendicular to the line passing through (-3,9) and (5,-1)?

Mar 22, 2016

$+ \frac{4}{5}$
Let the gradient of the first line be $m$
$m = \left(\text{change in y")/("change in x}\right) = \frac{- 1 - 9}{5 - \left(- 3\right)} = - \frac{10}{8} = - \frac{5}{4}$
The new line gradient is $- \frac{1}{m} = + \frac{4}{5}$