\(\left(1-\dfrac{1}{5}\right)\times\left(1-\dfrac{1}{6}\right)\times\left(1-\dfrac{1}{7}\right)\times\left(1-\dfrac{1}{8}\right)\times\left(1-\dfrac{1}{9}\right)\)
\(=\dfrac{4}{5}\times\dfrac{5}{6}\times\dfrac{6}{7}\times\dfrac{7}{8}\times\dfrac{8}{9}\)
\(=\dfrac{4}{9}\)
tính nhanh đúng ko?
= 4/5 x 5/6 x 6/7 x 7/8 x 8/9
= 4 x 5 x 6 x 7 x 8/ 5 x 6 x 7 x 8 x 9
= 4/9