posted by Ann .
Two charges are fixed in place with a separation d. One charge is positive and has nine times (n = 9) the magnitude of the other charge, which is negative. The positive charge lies to the left of the negative charge. Relative to the negative charge, locate the two spots on the line through the charges where the total potential is zero.
positive distance to the left of -q =?
positive distance to the right of -q =?
Potential is additive. Put the + charge at x=0.
Now, test the potential at x
V= k9q/x - kq/(d-x)
Set v to zero, and solve for x.