Tính một cách hợp lí:c) -3/10 -0,125+ -7/10 + 1,125b) -8/3. 2/11 - 8/3 : 11/9

* Hướng dẫn giải

$$\begin{gathered} a) \frac{-3}{10}-0,125+\frac{-7}{10}+1,125 \\ =\frac{-3}{10}+\frac{-7}{10}+1,125-0,125 \\ =-\left(\frac{3}{10}+\frac{7}{10}\right)+(1,125-0,125) \\ =-\frac{10}{10}+1 \\ = -1 + 1 = 0 \\ b) \frac{-8}{3}.\frac{2}{11}-\frac{8}{3}:\frac{11}{9} \\ =-\frac{8}{3}.\frac{2}{11}-\frac{8}{3}.\frac{9}{11} \\ =-\frac{8}{3}.\left(\frac{2}{11}+\frac{9}{11}\right) \\ =-\frac{8}{3}.1=-\frac{8}{3} \end{gathered}$$