\[\boxed{\mathbf{791}\mathbf{.}}\]
\[1)\log_{9}a^{4} = \log_{3^{2}}a^{4} =\]
\[= \frac{1}{2} \cdot 4\log_{3}a = 2\log_{3}a\ \]
\[2)\log_{\frac{1}{3}}a^{- 2} = \log_{3^{- 1}}\left( a^{2} \right)^{- 1} =\]
\[= - ( - 2)\log_{3}a = 2\log_{3}a\]
\[3)\log_{\sqrt{3}}a = \log_{3^{\frac{1}{2}}}a = 2\log_{3}a\]
\[4)\log_{\frac{1}{\sqrt{3}}}a^{2} = {\log_{3^{\frac{1}{2}}}a}^{2} =\]
\[= = 2 \cdot ( - 2)\log_{3}a = - 4\log_{3}a\]