\[\frac{1}{\sqrt{4x + 3}}\]
\[ОДЗ:\ 4x + 3 > 0\]
\[\ \ \ \ \ \ \ \ \ \ \ 4x > - 3\]
\[\ \ \ \ \ \ \ \ \ \ \ x > - \frac{3}{4}\]
\[Ответ:x \in \left( - \frac{3}{4}; + \infty \right)\text{.\ }\]