4 2 x - x ------- x - 1
(x^4 - x^2)/(x - 1)
x^2 + x^3
2 3 x + x
2 x *(1 + x)
x^2*(1 + x)
(x^4 - x^2)/(-1.0 + x)
2 / 2\ x *\-1 + x / ------------ -1 + x
x^2*(-1 + x^2)/(-1 + x)