Question

[Trần Ngọc Quỳnh]

A=1/2+1/4+1/8+1/16+1/32+...+1/268
               Giair cụ thể ra hộ mình nhé >.<
 

Answer 1

[Nguyễn Thị Thương Hoài]

      A  =          \(\dfrac{1}{2}\) + \(\dfrac{1}{4}\) +    \(\dfrac{1}{8}\) + \(\dfrac{1}{16}\) + \(\dfrac{1}{32}\)+.....+  \(\dfrac{1}{134}\)+ \(\dfrac{1}{268}\)

A \(\times\) 2 =  1  +  \(\dfrac{1}{2}\) + \(\dfrac{1}{4}\)   + \(\dfrac{1}{8}\)  + \(\dfrac{1}{16}\) + \(\dfrac{1}{32}\) +.....+ \(\dfrac{1}{134}\)

A \(\times\) 2 - A = 1 - \(\dfrac{1}{268}\)

A \(\times\) ( 2  - 1) = \(\dfrac{267}{268}\)

A = \(\dfrac{267}{268}\)