What is the slope that is perpendicular to 2x+8y=9?

Dec 23, 2014

First you change the equation into the form y=mx+b

$2 x$ to the other side: $8 y = - 2 x + 9$
divide by 8: y = $- \frac{1}{4} x + \frac{9}{8}$
Now the slope of the perpendicular (we'll call it mp):
Reverse the sign and flip the division:
$m p = + \frac{4}{1} = 4$