3(x-y)的2次方-9(x-y)-8(x-y)的2次方+6(x-y)-1合并同类项
问题描述：
3(x-y)的2次方-9(x-y)-8(x-y)的2次方+6(x-y)-1合并同类项
答
3(x-y)²-9(x-y)-8(x-y)²+6(x-y)-1
=(3-8)(x-y)²+(-9+6)(x-y)-1
=-5(x-y)²-3(x-y)-1
完毕