Đáp án:
$\begin{array}{l}
{\left( { - \dfrac{1}{2}} \right)^2}.\sqrt {\dfrac{{16}}{{25}}} + \sqrt {81} .{\left( {\dfrac{{ - 2}}{3}} \right)^2} - 1\\
= \dfrac{1}{4}.\dfrac{4}{5} + 9.\dfrac{4}{9} - 1\\
= \dfrac{1}{5} + 4 - 1\\
= \dfrac{{16}}{5}\\
\dfrac{1}{2}.\sqrt {\dfrac{4}{9}} = \dfrac{1}{2}.\dfrac{2}{3} = \dfrac{1}{3}
\end{array}$