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