b) (x^2y^2 – 3)(3 + x^2y^2).

b) (x²y² – 3)(3 + x²y²) = x²y² . 3 + x²y² . x²y² – 3 . 3 – 3 . x²y²

= 3x²y² + x⁴y⁴ – 9 – 3x²y² = x⁴y⁴ – 9.