Giải các phương trình :
$\begin{array}{l}
1)\,\,{x^{3 - \log \frac{x}{3}}} =
900\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,
\,\,\,3)\,\,{8^{{x^3} - 1}} + {18^{{x^3} - 1}} = {2.27^{{x^3} - 1}}\\
2)\,\,{49^{\frac{1}{x}}} - {35^{\frac{1}{x}}} =
{25^{\frac{1}{x}}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,4)\,\,{4.3^x} - {9.2^x} = {5.6^{\frac{x}{2}}}
\end{array}$