Вопрос:

Ответ:

\[x² - 6x + 9 \leq 0\]

\[(x - 3)^{2} \leq 0\]

\[(x - 3)^{2} = 0\]

\[x = 3\]

\[Ответ:\ \left\{ 3 \right\}.\]