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17 tháng 4 2023

\(B=\dfrac{1}{4}+\dfrac{1}{16}+\dfrac{1}{64}+...+\dfrac{1}{1024}\)

\(4B=1+\dfrac{1}{4}+\dfrac{1}{16}+...+\dfrac{1}{256}\)

\(4B-B=1-\dfrac{1}{1024}\)

\(3B=\dfrac{1023}{1024}\)

\(B=\dfrac{1023}{1024}:3\)

\(B=\dfrac{341}{1024}\)

17 tháng 4 2023

B=1/4+1/16+1/64+..+1/1024

B=1/4+1/4^2+1/4^3+....+1/4^5

4B=1+1/4^2+....+1/4^4

=>4B-B=1-1/4^5

=>3B=1-1/4^5

=>B=1/3-1/(4^5*3)

17 tháng 2 2022

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7 tháng 6 2015

gọi A=1/2+1/4+1/8+...+1/1024

2xA=1+1/2+1/4+.....+1/512

2xA-A=(1+1/2+1/4+....+1/512)-(1/2+1/4+1/8+...+1/1024)

A=1-1/1024

=1023/1024

vậy A=1023/1024

 

7 tháng 6 2015

\(\frac{1}{2}+\frac{1}{4}+...+\frac{1}{1024}=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{4}+...+\frac{1}{512}-\frac{1}{1024}=1-\frac{1}{1024}=\frac{1023}{1024}\)

21 tháng 5 2016

đặt  biểu thức là A ta có :

 A = 1/2 + 1/4  + 1/8 + 1/16 +1/32 +1/64 +1/128 + 1/256 + 1/512 + 1/102

A x 2 = 1+ 1/2 + 1/4 + 1/8 + 1/16 +1 /32+1/64 + 1/ 128 + 1/256 + 1/512 

A = ( 1 + 1/2 +1/4 + 1/ 8+ 1/16 + 1/32 + 1/64 + 1/128 + 1/256 + 1/512 ) - ( 1/2 + 1/4 + 1/8 +1/16 +1/32 + 1/64 + 1/128 +1/256 +1/512 +1/1024)

A = 1 - 1/1024 

A = 1023/1024

nhớ k nhé

21 tháng 5 2016

(1 / 2) + (1 / 4) + (1 / 8) + (1 / 16) + (1 / 32) + (1 / 64) + (1 / 128) + (1 / 256) + (1 / 512) + (1 / 1024) =

0.9990234375

12 tháng 6 2015

đề phải là 1 +1/2 + 1/4 +1/32 + 1/64 + 1/128 +1/256 +/512 +1/1024 moi dug 

13 tháng 9 2016

ngoi tinh phat chan

14 tháng 9 2016

tơ ghi sai

1 tháng 11 2021

bằng 0,9990234375

2 tháng 11 2021

1023/1024

24 tháng 7 2023

M = 1/4 + 1/16 + 1/64 + 1/256 + 1/1024 
4.M = 1 + 1/4 + 1/16 + 1/64 + 1/256 
4M - M = (1 + 1/4 + 1/16 + 1/64 + 1/256 ) - ( 1/4 + 1/16 + 1/64 + 1/256 + 1/1024 ) 
3M       = 1 - 1/1024 
 3M       = 1023/1024 
  M        = 341/1024

24 tháng 7 2023

M=\(\dfrac{1}{4}\)+\(\dfrac{1}{16}\)+\(\dfrac{1}{64}\)+\(\dfrac{1}{256}\)+\(\dfrac{1}{1024}\)

  =\(\dfrac{1}{4}\)+\(\dfrac{1}{4^2}\)+\(\dfrac{1}{4^3}\)+\(\dfrac{1}{4^4}\)+\(\dfrac{1}{4^5}\)

=>4M=1+\(\dfrac{1}{4}\)+\(\dfrac{1}{4^2}\)+\(\dfrac{1}{4^3}\)+\(\dfrac{1}{4^4}\)

=>4M-M=3M=(1+\(\dfrac{1}{4}\)+\(\dfrac{1}{4^2}\)+\(\dfrac{1}{4^3}\)+\(\dfrac{1}{4^4}\))-(\(\dfrac{1}{4}\)+\(\dfrac{1}{4^2}\)+\(\dfrac{1}{4^3}\)+\(\dfrac{1}{4^4}\)+\(\dfrac{1}{4^5}\))=1-\(\dfrac{1}{4^5}\)=\(\dfrac{1023}{1024}\)

=>M=\(\dfrac{1023}{1024}\):3=\(\dfrac{341}{1024}\)