合并同类项 2(x-y)²-3(x-y)+5(x-y)²+3(x-y)
问题描述：
合并同类项 2(x-y)²-3(x-y)+5(x-y)²+3(x-y)
答
2(x-y)²-3(x-y)+5(x-y)²+3(x-y)
= 2(x-y)²+5(x-y)²-3(x-y)+3(x-y)
=7(x-y)²