2 x - 2*x - 7
x^2 - 2*x - 7
2 -7 + x - 2*x
-7 + x^2 - 2*x
/ ___\ / ___\ \x + -1 + 2*\/ 2 /*\x + -1 - 2*\/ 2 /
(x - 1 + 2*sqrt(2))*(x - 1 - 2*sqrt(2))
-7 + x*(-2 + x)
-7.0 + x^2 - 2.0*x