Thực hiện phép tính a) (7 - 3 4/5) . 3 1/8 - 1 3/5 : (0,5)^2 b) |-1 5/8| + 1,25

* Hướng dẫn giải

a) $\left(7-3\frac{4}{5}\right).3\frac{1}{8}-1\frac{3}{5}:{\left(0,5\right)}^2$$=\left(7-\frac{19}{5}\right).\frac{25}{8}-\frac{8}{5}:{\left(\frac{1}{2}\right)}^2=\left(\frac{35}{5}-\frac{19}{5}\right).\frac{25}{8}-\frac{8}{5}.\frac{1}{4}$$=\frac{16}{5}.\frac{25}{8}-\frac{2}{5}=10-\frac{2}{5}=\frac{48}{5}.$

b) $\left|-\text{1}\frac{\text{5}}{\text{8}}\right|+\text{1,25:}\left(\text{1}-\frac{\text{9}}{\text{4}}\right)$ $=\left|\frac{-13}{8}\right|+\frac{125}{100}\text{:}\left(\frac{4}{4}-\frac{\text{9}}{\text{4}}\right)=\frac{13}{8}+\frac{5}{4}:\frac{-5}{4}$ $=\frac{13}{8}+\frac{5}{4}.\frac{-4}{5}=\frac{13}{8}+\left(-1\right)=\frac{5}{8}.$