先化简再求值 （x+y)^2(x-y)^2-(x^2+y^2)^2 其中x=2 y=-1/2
问题描述：
先化简再求值 （x+y)^2(x-y)^2-(x^2+y^2)^2 其中x=2 y=-1/2
答
解(x+y)²(x-y)²-(x²+y²)²=[(x+y)(x-y)]²-(x²+y²)²=(x²-y²)²-(x²+y²)²=[(x²-y²)-(x²+y²][(x²-y²)+(x...