Đáp án:
$\begin{array}{l}
\frac{{2x - 1}}{{2x + 1}}:\left( {2x - 1 + \frac{{2 - 4x}}{{2x + 1}}} \right)\\
= \frac{{2x - 1}}{{2x + 1}}:\left( {\frac{{\left( {2x - 1} \right)\left( {2x + 1} \right) + 2 - 4x}}{{2x + 1}}} \right)\\
= \frac{{2x - 1}}{{2x + 1}}.\frac{{2x + 1}}{{4{x^2} - 1 + 2 - 4x}}\\
= \frac{{2x - 1}}{{4{x^2} - 4x + 1}}\\
= \frac{{2x - 1}}{{{{\left( {2x - 1} \right)}^2}}} = \frac{1}{{2x - 1}}
\end{array}$
