Question

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

Answer 1

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 `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 `2/5` instead of `5/2`

But we must also remember the negative!!

So the slope of our perpendicular line is `-5/2`