9.064. $\left(\frac{2}{7}\right)^{3(2 x-7)} \cdot 12,25^{\frac{4 x+1}{2}} \geq 1$.
Solution.

From the condition

$$
\begin{aligned}
& \left(\frac{2}{7}\right)^{3(2 x-7)} \cdot\left(\frac{49}{4}\right)^{\frac{4 x+1}{2}} \geq 1 \Leftrightarrow\left(\frac{2}{7}\right)^{3(2 x-7)} \geq\left(\frac{2}{7}\right)^{4 x+1} \Leftrightarrow \\
& \Leftrightarrow 3 \cdot(2 x-7) \leq 4 x+1, x \leq 11
\end{aligned}
$$

Answer: $\quad x \in(-\infty ; 11]$