tính bằng cách thuận tiện nhất 

a,\(\frac{6}{7}\cdot\frac{16}{15}\cdot\frac{7}{6}\cdot\frac{21}{32}\)b, \(\frac{21}{17}\cdot\frac{13}{14}\cdot56\cdot\frac{3}{42}\)  c,\(\frac{7}{4}\cdot\frac{11}{21}+\frac{11}{21}\cdot\frac{5}{4}\)   d,\(\frac{23}{14}\cdot\frac{6}{14}-\frac{9}{14}\cdot\frac{6}{13}\)

Tìm các tích sau :

a/ \(\frac{16}{15}\times\frac{-5}{14}\times\frac{64}{24}\times\frac{56}{21}\)

b/ \(\frac{7}{3}\cdot\frac{-5}{2}\cdot\frac{15}{21}\cdot\frac{4}{-5}\)

\(\frac{16}{15}\cdot\frac{-5}{14}\cdot\frac{54}{24}\cdot\frac{56}{21}\)

Bài 1: Tính(hợp lý nếu có thể) e) \(\frac{5}{9}.\frac{7}{13}+\frac{5}{9}.\frac{9}{13}-\frac{5}{9}.\frac{3}{13}\) f)\(\frac{12}{19}\cdot\frac{7}{15}\cdot\frac{-13}{17}\cdot\frac{19}{12}\cdot\frac{17}{13}\) g) \(\left(\frac{-4}{5}+\frac{4}{3}\right)+\left(\frac{-5}{4}+\frac{14}{5}\right)-\frac{7}{3}\)

1. Tính tổng 

\(\frac{1}{2}\cdot\frac{1}{3}\cdot+\frac{1}{3}\cdot\frac{1}{4}+\frac{1}{4}\cdot\frac{1}{5}+\frac{1}{5}\cdot\frac{1}{6}+\frac{1}{6}\cdot\frac{1}{7}+\frac{1}{7}\cdot\frac{1}{8}+\frac{1}{8}\cdot\frac{1}{9}\)

\(\sqrt[2]{4\cdot9\frac{8}{8}+\frac{48\cdot11+5}{1\cdot\frac{814}{5+\frac{6145}{1\cdot\frac{821}{614}}}}}2548-\frac{8452}{14\cdot\frac{58}{96\cdot\frac{41}{\frac{24}{1\cdot\frac{975545}{1421+\frac{84874}{\frac{1+2+3+4+5+6+7+8+9\cdot2\cdot3\cdot4\cdot5\cdot6\cdot7\cdot8\cdot9}{2\cdot\frac{2}{1}}}}}}}}\)

tình hợp lí:

                \(\frac{\left(\frac{1}{5}-\frac{2}{7}\right)\cdot\frac{3}{4}-\frac{3}{4}\cdot\left(\frac{1}{3}-\frac{2}{7}\right)}{\frac{1}{5}\cdot\frac{2}{7}-\frac{1}{3}\cdot\left(\frac{2}{7}+\frac{3}{9}\right)+\frac{3}{9}+\frac{1}{5}}\)

3,Tính hợp lý

a,\(\frac{3}{7}\cdot\frac{4}{9}+\frac{3}{7}\cdot\frac{5}{9}+\frac{5}{14}\)

b,\(\frac{-11}{23}\cdot\frac{6}{7}+\frac{8}{9}\cdot\frac{-11}{23}-\frac{1}{23}\)

Giúp mình nhé!!!

tinh hop li :

                \(\frac{\left(\frac{1}{5}-\frac{2}{7}\right)\cdot\frac{3}{4}-\frac{3}{4}\cdot\left(\frac{1}{3}-\frac{2}{7}\right)}{\frac{1}{5}\cdot\frac{2}{7}-\frac{1}{3}\cdot\left(\frac{2}{7}+\frac{3}{9}\right)+\frac{3}{9}+\frac{1}{5}}\)