(1).(-2xy²)*(3x²y)²
=(-2xy²)*(9x^4y²)
=-18x^5y^4
(2).(-a)²(2-3ab)
=a²(2-3ab)
=2a²-3a³b
(3).(x+2y)(2x-y)
=x(2x-y)+2y(2x-y)
=2x²-xy+4xy-2y²
=2x²+3xy-2y²
(4).(a-2b)(a+2b)
=a²-(2b)²
=a²-4b²
(5).(2a+1)²
=(2a)²+2×2a×1+1²
=4a²+4a+1
(6).(a-3b)²
=a²-2a×3b+(3b)²
=a²-6ab+9b²