1、(x-y)(a-b)-(y-x)(2a-3b)=(x-y)(a-b)+(x-y)(2a-3b)=(x-y)(a-b+2a-3b)=(x-y)(3a-4b)2、-2x²y-4xy²-（3³y²+6x²y²）=-y(2x²+4xy+27y+6x²y)第2题对吗?