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