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