\[= \frac{4ab}{a^{2} - b^{2}} \bullet \left( \frac{- 2a \bullet 2b}{a^{2} - b^{2}} \right)^{- 1} =\]
\[Ответ:\ - 1.\]
\[5^{- 8} \bullet 5^{6} = 5^{- 8 + 6} = 5^{- 2} =\]
\[= \frac{1}{5^{2}} = \frac{1}{25}\]