问题描述: x+y=1,xy=-1/2,求x(x+y)(x-y)-x(x+y)2 1个回答 分类:数学 2014-11-14 问题解答: 我来补答 x(x+y)(x-y)-x(x+y)2 =x(x+y)[(x-y)-(x+y)]=x(x+y)(-2y)=-2xy(x+y)=-2×(-1/2)×1=1 再问: 18p3q3-2pq 再答: 7(x-1)3-14(x-1)2+7(x-1)=7(x-1)[﹙x-1﹚²-2﹙x-1﹚+1]=7﹙x-1﹚[﹙x-1﹚-1]² =7﹙x-1﹚﹙x-2﹚² 展开全文阅读