How underline 1/r come from ??

Consta ant vecto 29- 0 {Sum of total charge in zero} 1=1 P=P Electric field due to a dipole. we have potential due to dipole at arbitrary point (r, 0, o) in spherical polar coordinate as 1qdcos V(r,0,0) = Eo 2 Potential is symmetric of coordinate so E, will be zero. +q p -q as P-qd2 is in ż direction. Now E = - VV E,--V=- 1 Pcose or 4T Eo r EATEo r 1 2Pcos and E,=- P cose) r C4z e 1 Psin6 4T