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AH
Akai Haruma
Giáo viên
10 tháng 7 2022

Lời giải:
Gọi tổng trên là A

$A=1+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+...+\frac{1}{512}$

$2\times A=2+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+...+\frac{1}{256}$

$2\times A-A=(2+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+...+\frac{1}{256})-(1+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+...+\frac{1}{512})$

$A=2+\frac{1}{2}-(1+\frac{1}{512})$

$A=\frac{767}{512}$

17 tháng 2 2022

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8 tháng 4 2016

A= 1/2 + 1/4+ 1/8+ 1/16 + 1/32 + 1/64 + 1/128 + 1/256 + 1/512 
A = 1 - 1/2 + 1/2- 1/4 + 1/4 - 1/8 + 1/8 - 1/16 + 1/16 - 1/32 + 1/32 - 1/64 + 1/64 - 1/128 + 1/128 - 1/256 - 1/256 - 1/512 
A = 1 - 1/512 
A = 511/512 
Chúc bạn học giỏi nha!

8 tháng 4 2016

gọi biểu thức đó là A

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

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

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

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

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

1/512+A=1/2+1/4+1/8+1/16+1/32+1/32

1/512+A=1/2+1/4+1/8+1/16+1/16

1/512+A=1/2+1/4+1/8+1/8

1/512+A=1/2+1/4+1/4

1/512+A=1/2+1/2

1/512+A=1

A=1-1/512

A=511/512

chắc 100%

2 tháng 1

*Tham khảo 

14 tháng 9

b-1/2+1/4+1/8+1/16+1/32+1/64+1/128+1/256

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

18 tháng 10 2016

\(M=\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{512}\)

\(2M=1+\frac{1}{2}+\frac{1}{4}+...+\frac{1}{256}\)

\(2M-M=\left(1+\frac{1}{2}+\frac{1}{4}+...+\frac{1}{256}\right)-\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{512}\right)\)

\(M=1-\frac{1}{512}=\frac{511}{512}\)

5 tháng 9 2016

-1-1/2-1/4-1/8-1/16-1/32-1/64-1/128-1/256-1/512-1/1024=-1,9990234375

1/4 + 1/8 + 1/16 + 1/32 + 1/64 + 1/128 + 1/256 + 1/512

A x 2 = 1/4 ( 1/4 + 1/8 + 1/16 + .......... + 1/512 ) - 1/512

A x 2 = 1/4 - A - 1/512

A x 2 - A = 1/4 - 1/512

A = 1/4 - 1/512

A = 127/512

1/4 + 1/8 + 1/16 + 1/32 + 1/64 + 1/128 + 1/256 + 1/512

= 1/2 - 1/4 + 1/4 - 1/8 + ... + 1/256 - 1/512

= 1/2 - 1/512

= 255/512

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