Orbits in general relativity :
In the theory of general relativity, the path equation for a planet moving in the gravitational field of the Sun is, in the standard notation,
(d2u/dθ2) + u = (MG/L2) + (3MG/c2)u2,
where c is the speed of light. Find an approximation to the ‘annual' advance of the perihelion of a planet moving in a nearly circular orbit of radius a.