Two charges are placed along the x-axis; 3uC at 14 cm, and -4uC at 15 cm. Find those points along the x-axis where the potential is zero. (u = micro or 10^-6)
Andy, the r's in the equation is the distance from the particular charge up to the point where you want to calculate the potential. Write r2 in terms of r1 and the separation beween them before you solve for V1 = -V2. Try to solve for all three cases in between the two charges and on both sides outside of the two.