2 2 x - 3*y + x - 9*y
x - 3*y + x^2 - 9*y^2
1*(x - 3*y)*(x + 1 + 3*y)
(1*(x - 3*y))*(x + (1 + 3*y))
x + x^2 - 3.0*y - 9.0*y^2
(x - 3*y)*(1 + x + 3*y)