化简求值:[2x的平方-(x+y)(x-y)][(-x-y)(y-x)+2y的平方],其中x=1,y=2

分类: 作业答案 • 2023-01-10 17:16:11

问题描述：

答

[2x的平方-(x+y)(x-y)][(-x-y)(y-x)+2y的平方]=[2x²-(x²-y²)][(x+y)(x-y)+2y²]=(2x²-x²+y²)(x²-y²+2y²)=(x²+y²)/(x²+y²)=1