11) \(\frac{2m-3n}{m^2n}+\frac{7m-2n}{mn^2}\)

Общий знаменатель — \(m^2n^2\):

\[\frac{2m-3n}{m^2n}+\frac{7m-2n}{mn^2}=\frac{n(2m-3n)+m(7m-2n)}{m^2n^2}=\frac{7m^2-3n^2}{m^2n^2},\quad m\ne0,\ n\ne0.\]