Đáp án:
b) 3a
Giải thích các bước giải:
\(\begin{array}{l}
a)\dfrac{2}{{\left( {a - b} \right)\left( {a + b} \right)}}.\sqrt {\dfrac{{3{{\left( {a + b} \right)}^2}}}{2}} \\
= \dfrac{2}{{\left( {a - b} \right)\left( {a + b} \right)}}.\left| {a + b} \right|\sqrt {\dfrac{3}{2}} \\
= \dfrac{{\sqrt 2 .\sqrt 3 }}{{\left( {a - b} \right)\left( {a + b} \right)}}.\left( {a + b} \right)\\
= \dfrac{{\sqrt 6 }}{{a - b}}\\
b)\dfrac{2}{{1 - 2a}}.\sqrt {\dfrac{{9{a^2}.{{\left( {2a - 1} \right)}^2}}}{4}} \\
= \dfrac{2}{{1 - 2a}}.\dfrac{{3\left| a \right|.\left| {2a - 1} \right|}}{2}\\
= \dfrac{2}{{1 - 2a}}.\dfrac{{3a.\left( { - 2a + 1} \right)}}{2}\\
= \dfrac{{3a\left( {1 - 2a} \right)}}{{1 - 2a}} = 3a
\end{array}\)
