\[\sqrt{- x^{2} + 5x + 14}\]
\[- x^{2} + 5x + 14 \geq 0\]
\[x^{2} - 5x - 14 \leq 0\]
\[x_{1} + x_{2} = 5;\ \ x_{1} \cdot x_{2} = - 14\]
\[x_{1} = 7;\ \ x_{2} = - 2.\]
\[(x + 2)(x - 7) \leq 0\]
\[x = - 2;\ \ x = 7.\]
\[Ответ:\ x \in \lbrack - 2;7\rbrack.\]