Electric Potential (I think I'm close?)

1. Jul 23, 2008

1. The problem statement, all variables and given/known data
A -3.2 { nC} charge is on the x-axis at x_1 = -9 {cm} and a 14.6 {nC} charge is on the x-axis at x_2 = 16 {cm}.

***At what point or points on the y-axis is the electric potential zero?

2. Relevant equations
(1/4*pi*epsilon_0)*[(q1/r2) + (q2/r2)] = 0V

3. The attempt at a solution

The way I've tried solving it is by setting (q1/r2) = (q2/r2)
So 3.2*sqrt((16 cm)^2 + y^2) = 14.6*sqrt((-9 cm)^2 + y^2)
Eventually getting -14644.52 = 202.92 y^2
And y = +/- 8.5

Unfortunately this answer isn't being marked as correct. Does anyone see something wrong with the way I'm trying to solve this?

2. Jul 23, 2008

confuted

What happens when you square -9?

Hint: $$(y-y_0)^2$$