5 x - x
x - x^5
(x + 1)*x*(x - 1)*(x + I)*(x - I)
((((x + 1)*x)*(x - 1))*(x + i))*(x - i)
/ 4\ x*\1 - x /
x*(1 - x^4)
/ 2\ -x*(1 + x)*\1 + x /*(-1 + x)
-x*(1 + x)*(1 + x^2)*(-1 + x)