\[\frac{12x}{x + 4} - 5\sqrt{\frac{12x}{x + 4}} - 6 \geq 0\]
\[t = \sqrt{\frac{12x}{x + 4}}\]
\[t^{2} - 5t - 6 \geq 0\]
\[(t - 6)(t + 1) \geq 0\]
\[t \leq - 1;\ \ \ \ t \geq 6\]
\[1)\ \sqrt{\frac{12x}{x + 4}} \leq - 1;\ \ \ \ \]
\[\sqrt{\frac{12x}{x + 4}} \geq 0 \Longrightarrow нет\ решения.\]
\[2)\ \sqrt{\frac{12x}{x + 4}} \geq 6\]
\[\frac{12x}{x + 4} \geq 36\]
\[\frac{12x - 36 \cdot (x + 4)}{x + 4} \geq 0\]
\[\frac{12x - 36x - 144}{x + 4} \geq 0\]
\[\frac{- 24x - 144}{x + 4} \geq 0\]
\[\frac{- 24 \cdot (x + 6)}{x + 4} \geq 0\]
\[\frac{x + 6}{x + 4} \leq 0\]
\[Ответ:\lbrack - 6;\ - 4).\]