2 x - 2*x - 63
x^2 - 2*x - 63
2 -63 + x - 2*x
-63 + x^2 - 2*x
(x + 7)*(x - 9)
-63.0 + x^2 - 2.0*x
-63 + x*(-2 + x)
(-9 + x)*(7 + x)