\[\boxed{\mathbf{788}\mathbf{.}}\]
\[1)\ f(x) = x^{- 2}\]
\[f^{'}(x) = \left( x^{- 2} \right)^{'} = - 2 \bullet x^{- 2 - 1} =\]
\[= - 2 \bullet x^{- 3} = - \frac{2}{x^{3}}\]
\[2)\ f(x) = x^{- 3}\]
\[f^{'}(x) = \left( x^{- 3} \right)^{'} = - 3 \bullet x^{- 3 - 1} =\]
\[= - 3 \bullet x^{- 4} = - \frac{3}{x^{4}}\]
\[3)\ f(x) = x^{- 4}\]
\[f^{'}(x) = \left( x^{- 4} \right)^{'} = - 4 \bullet x^{- 4 - 1} =\]
\[= - 4 \bullet x^{- 5} = - \frac{4}{x^{5}}\]
\[4)\ f(x) = x^{- 7}\]
\[f^{'}(x) = \left( x^{- 7} \right)^{'} = - 7 \bullet x^{- 7 - 1} =\]
\[= - 7 \bullet x^{- 8} = - \frac{7}{x^{8}}.\]