化简；(x-y)(x+y)+(x-y)²+(x+y)²
问题描述：
化简；(x-y)(x+y)+(x-y)²+(x+y)²
答
(x-y)(x+y)+(x-y)²+(x+y)²=x²-y²+x²-2xy+y²+x²+2xy+y²=3x²+y²
化简；(x-y)(x+y)+(x-y)²+(x+y)²
(x-y)(x+y)+(x-y)²+(x+y)²=x²-y²+x²-2xy+y²+x²+2xy+y²=3x²+y²