\[1)\ y = \sqrt{\log_{3}\frac{2x + 1}{x - 6}}\]
\[\log_{3}\frac{2x + 1}{x - 6} \geq 0\]
\[\frac{2x + 1}{x - 6} \geq 1\]
\[\frac{(2x + 1) - (x - 6)}{x - 6} \geq 0\]
\[\frac{x + 7}{x - 6} \geq 0\]
\[x \leq - 7;\ \ \ x > 6.\]
\[Ответ:\ \ x \in ( - \infty;\ - 7\rbrack \cup (6;\ + \infty).\]
\[2)\ y = \sqrt{\log_{\frac{1}{2}}(x - 3) - 1}\]
\[\log_{\frac{1}{2}}(x - 3) - 1 \geq 0\]
\[\log_{0,5}(x - 3) \geq 1\]
\[0 < x - 3 \leq 0,5\]
\[3 < x \leq 3,5.\]
\[Ответ:\ \ x \in (3;\ 3,5\rbrack.\]