(y²-2a)(2a+y²)=(y²-2a)(y²+2a)=y⁴-4a²
(3x²+x)²=9x⁴+6x³+x²
(2+m)²(2-m)²=((2+m)(2-m))²=(4-m²)²=16-8m²+m⁴
