先化简,再求出它的值(4m+n)- [1-(m-4n)],其中m=2/5,n=-4/3

问题描述:

先化简,再求出它的值(4m+n)- [1-(m-4n)],其中m=2/5,n=-4/3

(4m+n)-[1-(m-4n)]
=4m+n-(1-m+4n)
=4m+n-1+m-4n
=5m-3n-1
=5×2/5-3×(-4/3)-1
=2+4-1
=5