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