\[\boxed{\mathbf{198}\mathbf{.}}\]
\[1)\ 5^{x} = \frac{1}{5}\]
\[5^{x} = 5^{- 1}\]
\[Ответ:\ \ x = - 1.\]
\[2)\ 7^{x} = 49\]
\[7^{x} = 7^{2}\]
\[Ответ:\ \ x = 2.\]
\[3)\ \left( \frac{1}{3} \right)^{x} = \sqrt{3}\]
\[3^{- x} = 3^{\frac{1}{2}}\]
\[- x = \frac{1}{2}\]
\[x = - 0,5.\]
\[Ответ:\ \ x = - 0,5.\]
\[4)\ \left( \frac{1}{7} \right)^{x} = \sqrt[3]{7}\]
\[7^{- x} = 7^{\frac{1}{3}}\]
\[- x = \frac{1}{3}\]
\[x = - \frac{1}{3}\]
\[Ответ:\ \ x = - \frac{1}{3}.\]