1) (x²+4)(x-2)(x+2)= (x²+4)(x²-4) = x⁴-16
2)(9a²+4)(2-3a)(3a+2)= (9a²+4)(4-9a²) = 16-81a⁴
3)(4p²+25)(5-2p)(2p+5) = (4p²+25)(25-4p²) = 625-16p²
4)(x-1)(x³-1)-3x(x-1)²= (x-1)(x-1)(x²+x+1)-3x(x-1)² = (x-1)²(x²+x+1)-3x(x-1)² = (x-1)²(x²+x+1-3x) = (x-1)²(x²-2x+1) = (x-1)²(x-1)² = (x-1)⁴