来自曹生现的问题
(x+y)²-2(x²-y²)+(y-x)²
(x+y)²-2(x²-y²)+(y-x)²
1回答
2020-01-27 02:02
(x+y)²-2(x²-y²)+(y-x)²
(x+y)²-2(x²-y²)+(y-x)²
(x+y)²-2(x²-y²)+(y-x)²
=(x+y)²-2(x+y)(x-y)+(x-y)²
=[(x+y)-(x-y)]²
=(2y)²
=4y²