[x^2-y^2],[x+y]^2,[-2x-2y]的公因式是
问题描述：
[x^2-y^2],[x+y]^2,[-2x-2y]的公因式是
答
x²-y²=(x+y)(x-y)
-2x-2y=-2(x+y)
还有一个(x+y)²
所以公因式是x+y