a, \(=\dfrac{1.2.3...5}{2.3...6}=\dfrac{1}{6}\)

cái 1 3 là 1/3 hả bạn?

cách là 1/3

ai có thể giúp mình đc ko

giúp mình đi khi nào bạn làm đúng thì mình sẽ thả like cho bạn

(1 + \(\dfrac{1}{49}\))\(\times\)(1 + \(\dfrac{1}{50}\))\(\times\)(1 + \(\dfrac{1}{51}\))\(\times\)(1 + \(\dfrac{1}{52}\))\(\times\)...\(\times\)(1 + \(\dfrac{1}{60}\))

= \(\dfrac{49+1}{49}\) \(\times\) \(\dfrac{50+1}{50}\)\(\times\) \(\dfrac{51+1}{51}\)\(\times\)\(\dfrac{52+1}{52}\)\(\times\)...\(\times\)\(\dfrac{61}{60}\)

= \(\dfrac{50}{49}\)\(\times\)\(\dfrac{51}{50}\)\(\times\)\(\dfrac{52}{51}\)\(\times\)...\(\times\)\(\dfrac{61}{60}\)

= \(\dfrac{50\times51\times52\times53\times...\times60}{50\times51\times52\times53\times...\times60}\)\(\times\)\(\dfrac{61}{49}\)

= \(\dfrac{61}{49}\)

cảm ơn

\(\left(1-\frac{1}{2}\right)\times\left(1-\frac{1}{3}\right)\times\left(1-\frac{1}{4}\right)\times...\times\left(1-\frac{1}{10}\right)\)

\(=\frac{1}{2}\times\frac{2}{3}\times\frac{3}{4}\times...\times\frac{9}{10}\)

\(=\frac{1}{10}\)

             \(\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right)...\left(1-\frac{1}{10}\right)\)

             \(=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.....\frac{9}{10}\)

             \(=\frac{1.2.3....9}{2.3.4...10}=\frac{1}{10}\)

             Ủng hộ mk nha !!! ^_^

(1-1/2) × (1-1/3) × (1-1/4) × (1-1/5) × (1-1/6)

=1/2 × 2/3 × 3/4 × 4/5 × 5/6 =1/6

\(=\dfrac{4}{5}\cdot\dfrac{5}{6}\cdot\dfrac{6}{7}\cdot\dfrac{7}{8}\cdot\dfrac{8}{9}=\dfrac{4}{9}\)

4/9

( 1 + 1/13 ) x ( 1 + 1/14 ) x ( 1 + 1/15 ) x ( 1 + 1/16 ) x ( 1 + 1/17 )

= 14/13 x 15/14 x 16/15 x 17/16 x 18/17

= 18/13