2 2 4*x ------ - --------- 2 2 x + 4 / 2 \ \x + 4/
2.0/(4.0 + x^2) - 4.0*x^2/(4.0 + x^2)^2
2 / 2\ 2 / 2\ 2*\4 + x / - 4*x *\4 + x / --------------------------- 3 / 2\ \4 + x /
/ 2\ 2*\4 - x / ---------- 2 / 2\ \4 + x /
2 8 - 2*x -------------- 4 2 16 + x + 8*x
-2*(-2 + x)*(2 + x) ------------------- 2 / 2\ \4 + x /
/ 2\ -\-8 + 2*x / -------------- 4 2 16 + x + 8*x