I couldn't understand the marked area...

A body is projected vertically upwards from 
the surface of the earth with a velocity equal 
to half the escape velocity the maximum 
height attained by the body is (Radius of 
earth = 6400 km) 
(A) 3240 km 
(B) 12800 km 
 (C) 2133 km 
(D) 6400 km 
Solution 
Using the law of conservation of energy, we 
have
 $\boxed{\frac{1}{2}m{\left(\frac{V_e}{2}\right)}^2-\frac{GMm}{R}=-\frac{GMm}{\left(R+H\right)}}$