\[\sqrt{\frac{x^{2} + 16x + 64}{x^{2} - 49}}\]
\[\frac{x^{2} + 16x + 64}{x^{2} - 49} \geq 0\]
\[\frac{(x + 8)^{2}}{(x + 7)(x - 7)} \geq 0\]
\[x < - 7;\ \ x > 7.\]
\[Ответ:x < - 7;\ \ x > 7.\]