1. The problem statement, all variables and given/known data Three charges lie along the x -axis. The positive charge q1 = 10.0 microC is at x = 1.00 m, and the negative charge q2 = -2.00 microC is at the origin. Where must a positive charge q3 be placed on the x-axis so that the resultant force on it is zero? Answer: x = - 0.809 m 2. Relevant equations Columb's Law F= k q1 q2 - - - - - - r^2 k = 8.9875 x 10^9 3. The attempt at a solution Force of 1 acting on 3 = - k q1 q3 / (1 - x)^2 Force of 2 acting on 3 = k q2 q3 / x^2 k q2 q3 / x^2 - k q1 q3 / (1 - x)^2 = 0 k's and q3's cancel out and I get q2(1 - x^2) = q1(x^2) -2(1 - 2x + x^2) = 10x^2 -2 + 4x - 2x^2 = 10x^2 12x^2 - 4x +2 = 0 x = .167 m Needing a bit of help in setting this one up perhaps. No solutions guide is available. Can someone have a more conceptual explanation on how to solve this one?