Thực hiện phép tính (tính hợp lí nếu có thể): (a) − 0 , 5 + 3/ 2

a) \( - 0,5 + \frac{3}{2} = - 0,5 + 1,5 = 1\);

b) \( - \frac{2}{5} - \frac{3}{5}.{\left( {\frac{5}{2}} \right)^2} = \frac{{ - 2}}{5} - \frac{3}{5}.\frac{{25}}{4} = \frac{{ - 2}}{5} - \frac{{15}}{4} = \frac{{ - 83}}{{20}}\);

c) \(\frac{7}{3}.\left( {\frac{{ - 5}}{9} + \frac{8}{{15}}} \right) + \frac{7}{3}.\left( {\frac{7}{{15}} - \frac{4}{9}} \right) = \frac{7}{3}.\left( {\frac{{ - 5}}{9} + \frac{8}{{15}} + \frac{7}{{15}} - \frac{4}{9}} \right)\)

\[ = \frac{7}{3}.\left[ {\left( {\frac{{ - 5}}{9} + \frac{{ - 4}}{9}} \right) + \left( {\frac{8}{{15}} + \frac{7}{{15}}} \right)} \right] = \frac{7}{3}.\left[ { - 1 + 1} \right] = 0\].