Giải thích các bước giải:
\(\begin{array}{*{20}{l}}
{B1.}\\
{a){\mkern 1mu} \frac{1}{{1 - x}} + \frac{{2x}}{{{x^2} - 1}}}\\
{ = \frac{{ - 1}}{{x - 1}} + \frac{{2x}}{{\left( {x - 1} \right)\left( {x + 1} \right)}}}\\
{ = {\rm{ }}\frac{{ - x - 1 + 2x}}{{\left( {x - 1} \right)\left( {x + 1} \right)}}}\\
{ = {\rm{ }}\frac{1}{{x + 1}}}\\
{2.}\\
{a){\mkern 1mu} \frac{1}{2}x\left( {{x^2} - 4} \right) = 0}\\
{ \Leftrightarrow \left[ {\begin{array}{*{20}{l}}
{x = 0}\\
{{x^2} - 4 = 0}
\end{array}} \right.}\\
{ \Leftrightarrow \left[ {\begin{array}{*{20}{l}}
{x = 0}\\
{\left( {x - 2} \right)\left( {x + 2} \right) = 0}
\end{array}} \right.}\\
{ \Leftrightarrow \left[ {\begin{array}{*{20}{l}}
{x = 0}\\
{x = 2}\\
{x = {\rm{ }} - 2}
\end{array}} \right.}
\end{array}\)
