Answer:
At the midpoint of the line joining the two equal charges
Explanation:
The midpoint of the line joining the two equal charges has equal distance from each charge. Since the charges are at x = a and x = -a, at the midpoint of the line joining the two equal charges, the magnitude of the electric field experienced as a result of each charge is the same. But these two fields are in opposite direction, hence the net resulting electric field would be equal to zero.
