化简2x(x-y﹚-5y﹙y-x﹚+3﹙x-y﹚².其中,x=-1,y=2

问题描述:

化简2x(x-y﹚-5y﹙y-x﹚+3﹙x-y﹚².其中,x=-1,y=2

2x(x-y﹚-5y﹙y-x﹚+3﹙x-y﹚²
=2x²-2xy-5y²+5xy+3x²-6xy+3y²
=5x²-3xy-2y²
=(5x+2y)(x-y)
=(-5+4)(-1-2)
=3谢谢哈