4 2 x - 5*x + 4
x^4 - 5*x^2 + 4
4 2 4 + x - 5*x
4 + x^4 - 5*x^2
(x + 2)*(x + 1)*(x - 1)*(x - 2)
(((x + 2)*(x + 1))*(x - 1))*(x - 2)
4.0 + x^4 - 5.0*x^2
(1 + x)*(-1 + x)*(-2 + x)*(2 + x)
2 / 2\ 4 + x *\-5 + x /
4 + x^2*(-5 + x^2)