Factor the following polynomial completely. - x^2y^2 + x^4 + 9y^2 - 9x^2

Move the pure terms to outside

x^4-9x^2-x^2y^2+9y^2

grop

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

undistribute common factors

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

reverse distributive

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

factor perfect squares

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