Two point charges lie along the y axis. A charge of q1 = -12.0 µC is at y = 6.0 m, and a charge of q2 = -5.0 µC is at y = -3.0 m. Locate the point (other than infinity) at which the total electric field is zero.

Answer 1

The are 9 meters apart. So to make it easier, we shift y axis up by adding 3.0, we will subtract it later.

k(-5)/x^2=k(-12/(9-x)^2

x is the distance from the lower charge.

12x^2=5(81+x^2-18x)
solve for x. Then add -3.