2 2 x - y - 6*x + 9
x^2 - y^2 - 6*x + 9
1*(x + -3 + y)*(x + -3 - y)
(1*(x - (3 + y)))*(x - (3 - y))
9.0 + x^2 - y^2 - 6.0*x
(-3 + x + y)*(-3 + x - y)