若m2-4mn+4n2=0,求m+n/m-n

问题描述:

若m2-4mn+4n2=0,求m+n/m-n

m^2-4mn+4n^2=0
==>(m-2n)^2=0
==>m=2n
m+n/m-n
=2n+n/2n-n
=3n/n
=3