a^2 + (4.0 - a^2)*(-2.0/(2.0 + a) + a/(-2.0 + a))
/ 2\ 2 \4 - a /*(4 - 2*a + a*(2 + a)) + a *(-2 + a)*(2 + a) ---------------------------------------------------- (-2 + a)*(2 + a)
/ 2\ 2 \4 - a /*(4 - 2*a + a*(2 + a)) + a *(-2 + a)*(2 + a) ---------------------------------------------------- (-2 + a)*(2 + a)