2 x + 4*x - 13
x^2 + 4*x - 13
/ ____\ / ____\ \x + 2 - \/ 17 /*\x + 2 + \/ 17 /
(x + 2 - sqrt(17))*(x + 2 + sqrt(17))
2 -13 + x + 4*x
-13 + x^2 + 4*x
-13 + x*(4 + x)
-13.0 + x^2 + 4.0*x