Question

tính giá trị biểu thức 

A, ( 1-1/2) (1 - 1/4 ) ( 1-1/5 ) ........(1- 1/2018) (1/2019)

giúp mk nha 

Answer 1

Trả lời

A=(1-1/2)(1-1/4)(1-1/5).....(1-1/2018)(1-1/2019)

=1/2.3/4.4/5......2017/2018.2018/2019

=1/2.1/2019

=1/4038.

Nhưng theo mk nghĩ đề phải như thế này>

A=(1-1/3)(1-1/4)(1-1/5)........(1-2018)(1-2019)

=2/3.3/4.4/5......2017/2018.2018/2019

=2/2019.

Answer 2

\(A=\left(1-\frac{1}{2}\right)\left(1-\frac{1}{4}\right).....\left(1-\frac{1}{2018}\right)\left(\frac{1}{2019}\right)\)

   \(=\frac{1}{2}.\frac{3}{4}.\frac{4}{5}.....\frac{2017}{2018}.\frac{1}{2019}=\frac{1}{2}.\frac{3}{2018}.\frac{1}{2019}=\frac{1}{2716228}\)

                 Vậy\(A=\frac{1}{2716228}\)

Answer 3

Bài làm

     \(\left(1-\frac{1}{2}\right)\left(1-\frac{1}{4}\right)\left(1-\frac{1}{5}\right)....\left(1-\frac{1}{2018}\right)\left(1-\frac{1}{2019}\right)\)

\(=\frac{1}{2}.\frac{3}{4}.\frac{4}{5}...\frac{2017}{2018}.\frac{2018}{2019}\)

\(=\frac{3}{2}.\frac{1}{2019}\)

\(=\frac{3}{4038}\)

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