Question

What is an equation in point-slope form for the line perpendicular to y=3x+9 that contains (-6,5)?

Answer 1

To be perpendicular, the slope of the new line has to have the reciprocal of the original slope.

Do this by flipping the slope (ifi t's a whole number make it a fraction) and change the sign.

3 ⇒ -1/3

Input x and y and solve for b.

5 = -1/3(-6) + b
Simplify.
5 = 2 + b
Subtract 2 from both sides.
3 = b

y = -1/3x + 3