把(x-y)看作一个整体,化简:(1)5(x-y)+2(x-y)-4(x-y);(2)3(x-y
问题描述：
把(x-y)看作一个整体,化简:(1)5(x-y)+2(x-y)-4(x-y);(2)3(x-y
²-4(x-y)+7（x-y)-6(x-y)
答
1、
5(x-y)+2(x-y)-4(x-y)=（5+2-4）（x-y）=3(x-y)
2、
3(x-y）²-4(x-y)+7（x-y)-6(x-y)=（3乘1-4+7-6）（x-y）=0