x2-y2,x2+2xy+y2,ax+ay-bx-by的公因式是萨
问题描述：
x2-y2,x2+2xy+y2,ax+ay-bx-by的公因式是萨
答
(x+y)(x-y)
(x+y)^2
a(x+y)-b(x+y)
=(a-b)(x+y)
所以是x+y