5.471. Выполните действия: а) (4/9 + 2/9) · 9/13; б) 2/3 · (9/8 − 3/4); в) (9/11 − 4/11) · 11/5; г) 2 · 1/8 + 7/12 · 3/7; д) (2/3)² + 13/21 · 7/26 − 5/18; е) (3/7 − 1/7)² · 49/16 + (1/2)³.

а) \(\left(\frac{4}{9}+\frac{2}{9}\right)\cdot\frac{9}{13}=\frac{6}{9}\cdot\frac{9}{13}=\frac{2}{3}\).

б) \(\frac{2}{3}\cdot\left(\frac{9}{8}-\frac{3}{4}\right)=\frac{2}{3}\cdot\frac{3}{8}=\frac{1}{4}\).

в) \(\left(\frac{9}{11}-\frac{4}{11}\right)\cdot\frac{11}{5}=\frac{5}{11}\cdot\frac{11}{5}=1\).

г) \(2\cdot\frac{1}{8}+\frac{7}{12}\cdot\frac{3}{7}=\frac{1}{4}+\frac{1}{4}=\frac{1}{2}\).

д) \(\left(\frac{2}{3}\right)^2+\frac{13}{21}\cdot\frac{7}{26}-\frac{5}{18}=\frac{4}{9}+\frac{1}{6}-\frac{5}{18}=\frac{1}{3}\).

е) \(\left(\frac{3}{7}-\frac{1}{7}\right)^2\cdot\frac{49}{16}+\left(\frac{1}{2}\right)^3=\frac{1}{4}+\frac{1}{8}=\frac{3}{8}\).