Tínha) (frac{{ - ,5}}{9},,.

* Hướng dẫn giải

a) \(\frac{{ - \,5}}{9}\,\,.\,\,\left( {\frac{3}{{10}}\, - \,\frac{2}{5}} \right)\)

\( = \frac{{ - \,5}}{9}\,\,.\,\left( {\frac{{ - 1}}{{10}}} \right) = \frac{5}{{90}}\)

b) \(\frac{1}{2}\sqrt {64}  - \sqrt {\frac{4}{{25}}} {\rm{ }} + {\rm{ }}{1^{2012}}\)

\( = \frac{1}{2}.8 - \frac{2}{5} + 1 = 4 - \frac{2}{5} + 1 = 5 - \frac{2}{5} = \frac{{23}}{5}\)