1 ------------ 2 x + 2*x + 1
1/(x^2 + 2*x + 1)
(1 + x)^(-2)
1 -------- 2 (1 + x)
1 ------------ 2 1 + x + 2*x
1/(1 + x^2 + 2*x)
1/(1.0 + x^2 + 2.0*x)
1 ------------- 1 + x*(2 + x)
1/(1 + x*(2 + x))