Thực hiện các phép tính sau: 2(5/7).4(1/5)

* Hướng dẫn giải

$a)2\frac{5}{7}.4\frac{1}{5}=\frac{19}{7}.\frac{21}{5}=\frac{57}{5}.\begin{array}{cccc}& & & \end{array}b)6\frac{5}{8}:2\frac{7}{4}=\frac{53}{8}:\frac{15}{4}=\frac{53}{30}$

$c)6\frac{7}{8}.\left(-2\frac{14}{9}\right)=\frac{55}{8}.\left(-\frac{32}{9}\right)=-\frac{220}{9}$

$d)1\frac{7}{8}:\left(-4\frac{1}{4}\right)=\frac{15}{8}:\left(-\frac{17}{4}\right)=-\frac{15}{34}$

$\begin{array}{l}e)\left(-4\frac{2}{9}\right).\left(-5\frac{1}{2}\right)=\left(-\frac{38}{9}\right).\left(-\frac{11}{2}\right)=\frac{209}{9}\\ \\ f)\left(-2\frac{8}{9}\right):\left(-4\frac{1}{3}\right)=\left(-\frac{26}{9}\right):\left(-\frac{13}{3}\right)=\frac{26}{39}\\ \\ g)3\frac{6}{5}.2=\left(3+\frac{6}{5}\right).2=3.2+\frac{6}{5}.2=6+\frac{12}{5}=\frac{42}{5}\\ \\ h)5\frac{4}{7}:2=\left(5+\frac{4}{7}\right):2=\frac{5}{2}+\frac{2}{7}=\frac{39}{14}\end{array}$