(3y²+1/2x)(1/2x-3y²)
=(1/2x+3y²)(1/2x-3y²)
=(1/2x)²-(3y²)²
=x²/4-9y⁴
(x-1/2)(x+1/2)(x²+1/4)
=(x²-1/4)(x²+1/4)
=x⁴-1/16
(x+y)(x-y)+(x+2y)(x-2y)
=x²-y²+x²-4y²
=2x²-5y²
(3y²+1/2x)(1/2x-3y²)
=(1/2x+3y²)(1/2x-3y²)
=(1/2x)²-(3y²)²
=x²/4-9y⁴
(x-1/2)(x+1/2)(x²+1/4)
=(x²-1/4)(x²+1/4)
=x⁴-1/16
(x+y)(x-y)+(x+2y)(x-2y)
=x²-y²+x²-4y²
=2x²-5y²