Question

is the equation of the directrix -9 in x^2=-36y?

Answer 1

I think you either meant to say x = -9 or y = -9 ?

Answer 2

However, neither of those is correct.

Answer 3

A drawing might help. Let's start with a blank xy axis

Answer 4

Then add on the graph of x^2 = -36y...which is really y = (-1/36)x^2. So it's going to be some parabola that opens downward (relatively widely) like this