Thực hiện các phép tính sau:a) (frac{{ - 2}}{{10}} + frac{{10}}{5} - frac{{ - 3}}{5})b) (frac{7}{{19}}.

* Hướng dẫn giải

a) 

\(\begin{array}{l}
{\rm{    }}\frac{{ - 2}}{{10}} + \frac{{10}}{5} - \frac{{ - 3}}{5}\\
 = \frac{{ - 2}}{{10}} + \left( {\frac{{10}}{5} - \frac{{ - 3}}{5}} \right)\\
 = \frac{{ - 2}}{{10}} + \frac{{13}}{5}\\
 = \frac{{ - 2}}{{10}} + \frac{{26}}{{10}}\\
 = \frac{{24}}{{10}} = \frac{1}{5}
\end{array}\)

b) 

\(\begin{array}{l}
\frac{7}{{19}}.\frac{8}{{11}} + \frac{7}{{19}}.\frac{3}{{11}} + \frac{{12}}{{19}}\\
 = \frac{7}{{19}}.\left( {\frac{8}{{11}} + \frac{3}{{11}}} \right) + \frac{{12}}{{19}}\\
 = \frac{7}{{19}}.\frac{{11}}{{11}} + \frac{{12}}{{19}}\\
 = \frac{7}{{19}}.1 + \frac{{12}}{{19}} = \frac{7}{{19}} + \frac{{12}}{{19}} = \frac{{19}}{{19}} = 1
\end{array}\)