Find the change in the force of gravity between two planets when the distance between them is decreased by a factor of 4.7

Answer 1

The mass of a certain neutron star is 3.4e+30 kg(around 1.5 solar masses) and its radius is 8400 m. What is the acceleration of gravity at the surface of this condensed, burned-out star? (Note on scientific notation: 3e+30 means 310^30.)

Answer 2

1) F = Gm1m2/r^2 since the only thing changing is r, F increases by (1/4.7)^2
2) g = GM/r^2