Three charges lie along the x-axis. The positive charge, q1 = 15 µC, is at x= 2.0 m, and The positive charge, q2 = 6.0 μC, is at the origin. At what point on the x-axis must a negative charge, q3 , be placed so that the net force acting on it is zero?

Answer 1

6 d^2 = 15 (20-d)^2 = 15 (400 - 40 d + d^2)

9 d^2 - 600 d + 6000 = 0

d is the distance in decimeters