4 2 x - 2*x + 1
x^4 - 2*x^2 + 1
4 2 1 + x - 2*x
1 + x^4 - 2*x^2
(x + 1)*(x - 1)
1.0 + x^4 - 2.0*x^2
2 2 (1 + x) *(-1 + x)
(1 + x)^2*(-1 + x)^2
2 / 2\ 1 + x *\-2 + x /
1 + x^2*(-2 + x^2)