2 x - 4*x - 1
x^2 - 4*x - 1
2 -1 + x - 4*x
-1 + x^2 - 4*x
/ ___\ / ___\ \x + -2 + \/ 5 /*\x + -2 - \/ 5 /
(x - 2 + sqrt(5))*(x - 2 - sqrt(5))
-1 + x*(-4 + x)
-1.0 + x^2 - 4.0*x