\[\boxed{\mathbf{7.}}\]
\[\left( 3^{x} - 2^{x} \right)^{2} + \left( 2^{x} - 1 \right)^{2} = 0\]
\[\left\{ \begin{matrix} 3^{x} - 2^{x} = 0 \\ 2^{x} - 1 = 0\ \ \\ \end{matrix} \right.\ \]
\[2^{x} = 1\]
\[2^{x} = 2^{0}\]
\[x = 0.\]
\[Проверим:\]
\[3^{0} - 2^{0} = 1 - 1 = 0.\]
\[Удовлетворяет.\]
\[Ответ:x = 0.\]
\[\left( 5^{x} - \frac{5}{2} \cdot 2^{x} \right)^{2} + \left( 2^{x} - 2 \right)^{2} = 0\]
\[\left\{ \begin{matrix} 5^{x} - \frac{5}{2} \cdot 2^{x} = 0 \\ 2^{x} - 2 = 0\ \ \ \ \ \ \ \ \\ \end{matrix} \right.\ \]
\[2^{x} = 2\]
\[x = 1.\]
\[Проверим:\]
\[5^{1} - \frac{5}{2} \cdot 2^{1} = 5 - 5 = 0.\]
\[Удовлетворяет.\]
\[Ответ:x = 1.\]