\[\boxed{\mathbf{297}\mathbf{.}}\]
\[1)\log_{3}x = 4\log_{3}a + 7\log_{3}b\]
\[\log_{3}x = \log_{3}a^{4} + \log_{3}b^{7}\]
\[\log_{3}x = \log_{3}\left( a^{4}b^{7} \right)\]
\[Ответ:\ \ x = a^{4}b^{7}.\]
\[2)\log_{5}x = 2\log_{5}a - 3\log_{5}b\]
\[\log_{5}x = \log_{5}a^{2} - \log_{5}b^{3}\]
\[\log_{5}x = \log_{5}\frac{a^{2}}{b^{3}}\]
\[Ответ:\ \ x = \frac{a^{2}}{b^{3}}.\]
\[3)\log_{\frac{1}{2}}x = \frac{2}{3}\log_{\frac{1}{2}}a - \frac{1}{5}\log_{\frac{1}{2}}b\]
\[\log_{\frac{1}{2}}x = \log_{\frac{1}{2}}\sqrt[3]{a^{2}} - \log_{\frac{1}{2}}\sqrt[5]{b}\]
\[\log_{\frac{1}{2}}x = \log_{\frac{1}{2}}\frac{\sqrt[3]{a^{2}}}{\sqrt[5]{b}}\]
\[Ответ:\ \ x = \frac{\sqrt[3]{a^{2}}}{\sqrt[5]{b}}.\]
\[4)\ \log_{\frac{2}{3}}x = \frac{1}{4}\log_{\frac{2}{3}}a + \frac{4}{7}\log_{\frac{2}{3}}b\]
\[\log_{\frac{2}{3}}x = \log_{\frac{2}{3}}\sqrt[4]{a} + \log_{\frac{2}{3}}\sqrt[7]{b^{4}}\]
\[\log_{\frac{2}{3}}x = \log_{\frac{2}{3}}\left( \sqrt[4]{a} \bullet \sqrt[7]{b^{4}} \right)\]
\[Ответ:\ \ x = \sqrt[4]{a} \bullet \sqrt[7]{b^{4}}.\]