Question

three point charges lie along the x axis as shown in the figure (no figure was given). the positive charge q1=15 mc is at x=2 m, the positive charge q2 =6 mc is at the origin, and the resultant force acting on q3 is 0. what is the x coordinate of q3?

Answer 1

$x=\frac{2\sqrt{q_{2}}}{\sqrt{q_{1}}+\sqrt{q_{2}}}=\frac{2\sqrt{6mC}}{\sqrt{15mC}+\sqrt{6mC}}$

or

${\color{Blue} x=0.77485 \, m=0.775\, m}$