Factor the following polynomial completely. - x2y2 + x4 + 9 y2 - 9 x2 (x - 3) (x - 3) (x + y) (x - y) (x + 3) (x + 3) (x + y) (x - y) (x + 3) (x - 3) (x + y) (x - y)

(x + 3) (x - 3) (x + y) (x - y)

Step-by-step explanation:

You can group the terms in pairs and factor each pair:

-x^2y^2 + x^4 + 9y^2 - 9x^2 = x^2 (-y^2+x^2) - 9 (-y^2+x^2)

= (x^2 - 9) (x^2 - y^2)

Each of these factors is the difference of squares, so can be factored as such:

= (x + 3) (x - 3) (x + y) (x - y)