【1】(3a^2b^2)+(-2ab)(-4a^3b)【2】(-5/2xy)×(2/3xy^2
【1】(3a^2b^2)+(-2ab)(-4a^3b)
【2】(-5/2xy)×(2/3xy^2-2xy+4/3y)
【3】(x-y)^4×(y-x)^3×(x-y)