x -------- 3 (x + 1)
x/(x + 1)^3
(1 + x)^(-2) - 1/(1 + x)^3
1 1 -------- - -------- 2 3 (1 + x) (1 + x)
x/(1.0 + x)^3
x ------------------- 3 2 1 + x + 3*x + 3*x
x/(1 + x^3 + 3*x + 3*x^2)