Question

1. Thực hiện phép tính (bằng cách hợp lí nếu có thể)

a. \(\frac{2}{17}\) + \(\frac{7}{21}\) + \(\frac{15}{17}\) - \(\frac{7}{5}\) + \(\frac{2}{3}\)                                                b. \(\frac{3}{4}\) . \(\frac{11}{5}\) - \(\frac{3}{4}\). \(\frac{31}{5}\) + \(\sqrt{81}\)

c.(-2)³ . (\(\frac{3}{4}\) - 0,25) : \(2\frac{1}{4}\)

Answer 1

a) \(\frac{2}{17}+\frac{7}{21}+\frac{15}{17}-\frac{7}{5}+\frac{2}{3}=\left(\frac{2}{17}+\frac{15}{17}\right)+\left(\frac{1}{3}+\frac{2}{3}\right)-\frac{7}{5}=1+1-\frac{7}{5}=\frac{3}{5}\)

b) \(\frac{3}{4}\cdot\frac{11}{5}-\frac{3}{4}\cdot\frac{31}{5}+\sqrt{81}=\frac{3}{4}\left(\frac{11}{5}-\frac{31}{5}\right)+9=\frac{3}{4}\cdot\left(-4\right)+9=-3+9=6\)

c) \(\left(-2\right)^3\cdot\left(\frac{3}{4}-0,25\right):2\frac{1}{4}=-8\cdot\frac{1}{2}:\frac{9}{4}=-8\cdot\frac{2}{9}=-\frac{16}{9}\)