\[\left( \sqrt[3]{x} \right)^{3} - \left( \sqrt[3]{3} \right)^{3} = \sqrt{x} + 9\]
\[x - 3 = \sqrt{x} + 9\]
\[x - \sqrt{x} - 3 - 9 = 0\]
\[x - \sqrt{x} - 12 = 0\]
\[t = \sqrt{x};\ \ \ \ \ t \geq 0\]
\[t^{2} - t - 12 = 0\]
\[t_{1} = 4;\ \ \ \ \]
\[t_{2} = - 3\ (не\ подходит).\]
\[\sqrt{x} = 4 \Longrightarrow x = 16.\]
\[Ответ:\ \ x = 16.\]