因为m/n=5/3所以可设m=5k,n=3k所以m/(m+n)+m/(m-n)-n^2/(m^2-n^2)=m(m-n)/(m^2-n^2)+m(m+n)/(m^2-n^2)-n^2/(m^2-n^2)=(m^2-mn+m^2+mn-n^2)/(m^2-n^2)=(2m^2-n^2)/(m^2-n^2)=(50k^2-9k^2)/(25k^2-9k^2)=41/16