Question

Пож, надо (mn^-1-nm^-1)(m+n)^-1*n/m-n

Answer 1

$( mn^{-1}- nm^{-1} )(m+n)^{-1}* \frac{n}{m-n}= ( \frac{m}{n}- \frac{n}{m} )* \frac{1}{m+n}* \frac{n}{m-n}=$$\frac{ m^{2} - n^{2} }{nm}*\frac{1}{m+n}* \frac{n}{m-n}= \frac{( m^{2}- n^{2} )*n}{mn*(m+n)*(m-n)} =\frac{( m^{2}- n^{2} )}{m(m+n)*(m-n)} =$$\frac{( m^{2}- n^{2} )}{m(m+n)*(m-n)} =\frac{( m+n)(m-n)}{m(m+n)(m-n)}= \frac{1}{m}= m^{-1}$