Question

(\(1\)-\(\dfrac{1}{3}\))\(\cdot\)(1-\(\dfrac{1}{6}\))\(\cdot\)(1-\(\dfrac{1}{10}\))\(\cdot\)(1-\(\dfrac{1}{15}\))\(\cdot\)(1-\(\dfrac{1}{21}\))\(\cdot\)(1-\(\dfrac{1}{28}\))

Answer 1

giúp mình với

Answer 2

\(\left(1-\dfrac{1}{3}\right)\left(1-\dfrac{1}{6}\right)\left(1-\dfrac{1}{10}\right)\left(1-\dfrac{1}{15}\right)\left(1-\dfrac{1}{21}\right)\left(1-\dfrac{1}{28}\right)\)

\(=\left(\dfrac{3}{3}-\dfrac{1}{3}\right)\left(\dfrac{6}{6}-\dfrac{1}{6}\right)\left(\dfrac{10}{10}-\dfrac{1}{10}\right)\left(\dfrac{15}{15}-\dfrac{1}{15}\right)\left(\dfrac{21}{21}-\dfrac{1}{21}\right)\left(\dfrac{28}{28}-\dfrac{1}{28}\right)\)

\(=\dfrac{2}{3}.\dfrac{5}{6}.\dfrac{9}{10}.\dfrac{14}{15}.\dfrac{20}{21}.\dfrac{27}{28}\)