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