(2m/4m^2-n^2)+(1/n-2m)= ( 2m/ (2m-n)*(2m+n) - (1/2m-n)= (2m-2m-n)/ (2m-n)*(2m+n)=- (n/ (2m-n)*(2m+n))=-(n/4m^2-n^2)
(2m/4m^2-n^2)+(1/n-2m)= ( 2m/ (2m-n)*(2m+n) - (1/2m-n)= (2m-2m-n)/ (2m-n)*(2m+n)=- (n/ (2m-n)*(2m+n))=-(n/4m^2-n^2)