b) (x^2y^2 – 3)(3 + x^2y^2).
b) (x2y2 – 3)(3 + x2y2).
b) (x2y2 – 3)(3 + x2y2) = x2y2 . 3 + x2y2 . x2y2 – 3 . 3 – 3 . x2y2
= 3x2y2 + x4y4 – 9 – 3x2y2 = x4y4 – 9.