GMem/(Re+h)2 = mv2/(Re+h)
Re = R = h
GMem/(2R)2 = mv2/(2R)
Let us first find the total Energy of the satellite.
Total Energy = Kinetic Energy + Potential Energy
= 1/2 mv2 + (-GMem/2R)
= 1/2 m (GMe/2R) - GMem/2R
= -GMem/4R
For orbit of Radius 4R
Total energy = -GMem/4 (4R) =-GMem/16R
Change in energy = -GMem/16R+GMem/4R=-3GMem/16 R
Comparing from given equation
k = 16/3
Regards