x --------- 2 / 2 \ \x + 1/
x/(x^2 + 1)^2
x/(1 + x^2)^2
x --------- 2 / 2\ \1 + x /
x/(1.0 + x^2)^2
x ------------- 4 2 1 + x + 2*x
x/(1 + x^4 + 2*x^2)