问题描述: 已知 m-n=4,mn=-1 .求(-2mn+2m+3n)-(3mn+2n-2m)-(m+4n+mn)的值 1个回答 分类:数学 2014-12-15 问题解答: 我来补答 (-2mn+2m+3n)-(3mn+2n-2m)-(m+4n+mn)=-2mn+2m+3n-3mn-2n+2m-m-4n-mn=(-2mn-3mn-mn)+(2m+2m-m)+(3n-2n-4n)=-6mn+3m-3n=3(m-n-2mn)原式=3[4-2(-1)]=3×6=18应该是这样 展开全文阅读