Thực hiện phép tínha) (frac{1}{{ - 4}} - frac{4}{{ - 3}} + frac{1}{{ - 3}} cdot left( {50\%  - 1frac{3}{2}} ight))b)&nbs

* Hướng dẫn giải

a) \(\frac{1}{{ - 4}} - \frac{4}{{ - 3}} + \frac{1}{{ - 3}} \cdot \left( {50\%  - 1\frac{3}{2}} \right)\)

\(\begin{array}{l}
 = \frac{{ - 1}}{4} + \frac{4}{3} + \frac{{ - 1}}{3}.\left( {\frac{1}{2} + \frac{{ - 5}}{2}} \right)\\
 = \frac{{ - 1}}{4} + \frac{4}{3} + \frac{{ - 1}}{3} \cdot ( - 2)\\
 = \frac{{ - 1}}{4} + \left( {\frac{4}{3} + \frac{2}{3}} \right) = \frac{{ - 1}}{4} + 2\\
 = 1\frac{4}{4} - \frac{1}{4} = 1\frac{3}{4}
\end{array}\)

b) \( - 1,4 \cdot \frac{{15}}{{ - 49}} - \left( {\frac{2}{5} + \frac{4}{3}} \right):2\frac{3}{5}\)

\(\begin{array}{l}
 = \frac{{ - 7}}{5}.\frac{{15}}{{ - 49}} - \left( {\frac{2}{5} + \frac{4}{3}} \right):\frac{{13}}{5}\\
 = \frac{{( - 7).15}}{{5.( - 49)}} - \frac{{26}}{{15}} \cdot \frac{5}{{13}}\\
 = \frac{3}{7} - \frac{2}{3}\\
 = \frac{9}{{21}} + \frac{{ - 14}}{{21}} = \frac{{ - 5}}{{21}}
\end{array}\)