\[\boxed{\mathbf{16.}}\]
\[36x^{2} + 7 = 35x^{2} + 16\]
\[x^{2} = 9\]
\[x = \pm 3.\]
\[x = 3 - не\ подходит;\]
\[x = - 3 - корень.\]
\[2)\ \left\{ \begin{matrix} \sqrt{2 - x} = 0\ \ \ \ \ \ \\ 36x^{2} + 7 \geq 0\ \ \\ 35x^{2} + 16 \geq 0 \\ \end{matrix} \right.\ \]
\[\left\{ \begin{matrix} x = 2 \\ x \in R \\ \end{matrix} \right.\ .\]
\[Ответ:x = - 3;x = 2.\]
\[\left\{ \begin{matrix} \sqrt{26x^{2} + 1} = \sqrt{25x^{2} + 17} \\ x \leq 3\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \\ \end{matrix} \right.\ \]
\[26x^{2} + 1 = 25x^{2} + 17\]
\[x^{2} = 16\]
\[x = \pm 4.\]
\[x = - 4 - корень;\]
\[x = 4 - не\ подходит.\]
\[2)\ \left\{ \begin{matrix} \sqrt{3 - x} = 0\ \ \ \ \ \ \ \\ 26x^{2} + 1 \geq 0\ \ \\ 25x^{2} + 17 \geq 0 \\ \end{matrix} \right.\ \]
\[\left\{ \begin{matrix} x = 3 \\ x \in R \\ \end{matrix} \right.\ \]
\[Ответ:x = - 4;x = 3.\]