# What is the slope of the line perpendicular to y=5/2x-9 ?

Feb 24, 2016

Remember that the slope of a perpendicular line is the NEGATIVE RECIPROCAL of another line.

From the line that we are given, we can see that the slope is clearly $\frac{5}{2}$ (y = mx + b where m is the slope)

So, now we just take the negative reciprocal.

A reciprocal is just flipping the fraction upside down

So we have $\frac{2}{5}$ instead of $\frac{5}{2}$

But we must also remember the negative!!

So the slope of our perpendicular line is $- \frac{5}{2}$