n4mn的精选

问题详情：若m-n=4,mn=-1,求(-2mn+2m+3n)-(3mn+2n-2m)-(m+4n+mn)的值.【回答】 (3)(-2mn+2m+3n)-(3mn+2n-2m)-(m+4n+mn)=-2mn+2m+3n-3mn-2n+2m-m-4n-mn=-6mn+3(m-n).当m-n=4,mn=-1时,原式=-6×(-1)+3×4=18.知识点：整式...