Three point charges are placed at the following locations: +4q at the origin, -2q at (x = -2, y = 0, z = 0) and -20 at (x = 2, y = 0 and z = 0). a. find the force on a fourth charge 5q placed at (x = 4, y = 6, z = 2) 6. find the force on a fourth charge 5q placed at (x, y, z) c. find locations where the force is solely in the (i) x direction, (ii) y direction, (iii) z direction d. is there any place where the force on the test charge is zero?