Решите неравенство: x-10*корень из x+9<=0.

\[x - 10\sqrt{x} + 9 \leq 0;\ \ \ t = \sqrt{x}\]

\[t^{2} - 10t + 9 \leq 0\]

\[(t - 9)(t - 1) \leq 0\]

\[1 \leq t \leq 9 \Longrightarrow 1 \leq \sqrt{x} \leq 9 \Longrightarrow\]

\[\Longrightarrow 1 \leq x \leq 81\]

\[Ответ:\lbrack 1;81\rbrack.\]