Consider two dipoles are placed at two points A and B in opposite direction.
Let P be the null point, where net electric field intensity is found to be zero. x be distance of point from electric dipole at A. By using expression of electric field intensity at axial position due to short electric dipole, E=
2kp
r3
E1 and E2 be the magnitudes of electric field due to electric dipole p and 27p. which are equal and opposite to produce net electric field zero. Therefore, E1=E2