Hãy rút gọn: \(\sqrt {\dfrac{{2a}}{3}.} \sqrt {\dfrac{{3a}}{8}}\).

* Hướng dẫn giải

 \(\sqrt {\dfrac{{2a}}{3}.} \sqrt {\dfrac{{3a}}{8}}\)

\(= \sqrt {\dfrac{{2a}}{3} \cdot \dfrac{{3a}}{8}} \)

\(= \sqrt {\dfrac{{6{a^2}}}{{24}}} \)

\(= \sqrt {\dfrac{{{a^2}}}{4}}\)

\(= \left| {\dfrac{a}{2}} \right|\)

Do \(a \ge 0\) nên  \(\left| {\dfrac{a}{2}} \right| = \dfrac{a}{2}\)

Vậy \(\sqrt {\dfrac{{2a}}{3}.} \sqrt {\dfrac{{3a}}{8}} = \dfrac{a}{2}\)