1.(-2a²)(3ab²-5ab³)
＝-6a³b²+10a³b³
2.(3y+2)(y-4)-3(y-2)(y-3)
=3y²-10y-8-3(y²-5y+6)
=3y²-10y-8-3y²+15y-18
=5y-26
3.(2x+y)²-(2x+3y)(2x-3y)
=4x²+4xy+y²-(4x²-9y²)
=4x²+4xy+y²-4x²+9y²
=4xy+10y²
4.(x+2y-3)(x-2y+3)
=[x+(2y-3)]×[x-(2y-3)]
=x²－(2y-3)²
=x²－(4y²-12y+9)
=x²－4y²+12y-9
5.(3x+1)²(3x-1)²
=[(3x+1)(3x-1)]²
=(9x²－1)²
=(81x^4)-18x²+1