a) ĐKXĐ: \(\left\{ \begin{array}{l}3x + 1 > 0\\2x + 1 > 0\\3x + 1 \ne 1\\2x + 1 \ne 1\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}x > - \dfrac{1}{3}\\x > - \dfrac{1}{2}\\x \ne 0\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}x > - \dfrac{1}{3}\\x \ne 0\end{array} \right.\)
TXĐ: \(D = \left( { - \dfrac{1}{3}; + \infty } \right)\backslash \left\{ 0 \right\}\)
b) ĐKXĐ:
\(\begin{array}{l}\left\{ \begin{array}{l}3x + 2 \ge 0\\3x + 2 \ne 1\\1 - \sqrt {1 - 4{x^2}} > 0\\1 - 4{x^2} \ge 0\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}x > - \dfrac{2}{3}\\x \ne - \dfrac{1}{3}\\\sqrt {1 - 4{x^2}} < 1\\1 - 4{x^2} \ge 0\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}x > - \dfrac{2}{3}\\x \ne - \dfrac{1}{3}\\1 - 4{x^2} < 1\\4{x^2} \le 1\end{array} \right.\\ \Leftrightarrow \left\{ \begin{array}{l}x > - \dfrac{2}{3}\\x \ne - \dfrac{1}{3}\\ - \dfrac{1}{2} \le x \le \dfrac{1}{2}\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l} - \dfrac{2}{3} < x \le \dfrac{1}{2}\\x \ne - \dfrac{1}{3}\end{array} \right.\end{array}\)
TXĐ: \(D = \left( { - \dfrac{2}{3};\dfrac{1}{2}} \right)\backslash \left\{ { - \dfrac{1}{3}} \right\}\)
