(-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=-6mn+3(m-n)将m-n=4,mn=-1代入=-6mn+3(m-n)=-6×(-1)+3×4=-6+7=1