The gravitational potential due to the system is given as V=r2k​ Gravitational field due to the system :E=−drdV​​⇒E=−drd​(r2k​)=−(−r32k​)⇒E=r32k​​ We can see that for this system, E∝r31​ This type of system is not possible because Fg​ is always proportional to inverse of square of distance(experimental fact).If there were negative masses, then this type of system is possible.This system is a dipole of two masses, i.e., two masses, one positive and the other negative, separated by a small distance.In this case, the gradational field due to the dipole is proportional to Fg​