\[\sqrt{5x + 3} + \frac{1}{\sqrt{6 - x}}\]
\[\left\{ \begin{matrix} 5x + 3 \geq 0 \\ 6 - x > 0\ \ \ \\ \end{matrix} \right.\ \]
\[\left\{ \begin{matrix} 5x \geq - 3\ \\ - x > - 6 \\ \end{matrix} \right.\ \]
\[\left\{ \begin{matrix} x \geq - 0,6 \\ x < 6\ \ \ \ \ \ \\ \end{matrix} \right.\ \]
\[- 0,6 \leq x < 6.\]
\[Ответ:\ - 0,6 \leq x < 6.\]