Question

Tính nhanh:

E= \(\frac{-2}{3}\). \(\frac{-5}{6}\). \(\frac{-9}{10}\). \(\frac{-14}{15}\). \(\frac{-20}{21}\). \(\frac{-27}{28}\). \(\frac{-35}{36}\).

Answer 1

\(E=\left(\frac{-2}{3}.\frac{-9}{10}\right).\left(\frac{-5}{6}.\frac{-14}{15}\right).\left(\frac{-20}{21}.\frac{-27}{28}\right).\frac{-35}{36}\)

\(E=\frac{3}{5}.\frac{7}{9}.\frac{45}{49}.\frac{-35}{36}\)

\(E=\left(\frac{3}{5}.\frac{-35}{36}\right).\left(\frac{7}{9}.\frac{45}{49}\right)\)

\(E=\frac{-7}{12}.\frac{5}{7}\)

\(E=\frac{-5}{12}\)

vậy \(E=\frac{-5}{12}\)

Answer 2

E=-2/3.-5/6.-9/10.-14/15.-20/21.-27/28.-35/36

=-2/3.-5/2.3.-3.3/2.5.-2.7/3.5.-4.5/3.7.3.3.3/4.7.-5.7/4.3.3

=-5/12

Answer 3

lại cảm ơn mi nhé hưởng he he he