Question

Rút gọn: B = (1-1/2).(1-1/3).(1-1/4).....(1-1/20)

Ai nhanh mk tích

Answer 1

=1/2.2/3.3/4.4/5.......19/20=1/20

Answer 2

B=1/2.2/3.3/4.4/5.....19/20

  = 1/20

Nha bạn      

Answer 3

Bạn trừ ra rùi rút gọn là đc

Answer 4

\(B=\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right)....\left(1-\frac{1}{20}\right)\)

\(B=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}....\frac{19}{20}\)

\(B=\frac{1.2.3.....19}{2.3.4...20}=\frac{1.\left(2.3.4....19\right)}{\left(2.3.4.....19\right).20}=\frac{1}{20}\)

Answer 5

\(B=\left(1-\frac{1}{2}\right)\cdot\left(1-\frac{1}{3}\right)\cdot\left(1-\frac{1}{4}\right)\cdot...\cdot\left(1-\frac{1}{20}\right)\)

\(B=\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{3}{4}\cdot...\cdot\frac{19}{20}\)

\(B=\frac{1}{20}\)