Giải thích các bước giải:
\(\begin{array}{l}
a.DK:2\left( {x - 1} \right) - 3\left( {2x + 1} \right) \ne 0\\
\to 2x - 2 - 6x - 3 \ne 0\\
\to - 4x \ne 5 \to x \ne - \frac{5}{4}\\
b.DK:1,2\left( {x + 0,7} \right) - 4\left( {0,6x + 0,9} \right) \ne 0\\
\to 1,2x + \frac{{21}}{{25}} - \frac{{12}}{5}x - \frac{{18}}{5} \ne 0\\
\to - \frac{6}{5}x \ne \frac{{69}}{{25}}\\
\to \ne - \frac{{23}}{{10}}
\end{array}\)