Question

Tìm x biết:

x:1/2+x:1/4+x:1/8+.......+x:1/512=511

 

Answer 1

x : 1/2 + x : 1/4 + x : 1/8  + ... + x : 1/512 = 511

=> 2x + 4x + 8x + ... + 512x = 511

=> x(2 + 4 + 8 + ... + 512) = 511

=> 65792x = 511

=> x = 511/65792

mjnh không chắc tại kết quả  lẻ quá

Answer 2

\(x:\frac{1}{2}+x:\frac{1}{4}+x:\frac{1}{8}+...+x:\frac{1}{512}=511\)

\(x.2+x.4+x.8+...+x.512=511\)

\(x.\left(2+4+8+...+512\right)=511\)

\(x.65792=511\)

                \(x=\frac{511}{65792}\)

Answer 3

x:1/2+x:1/4+x:1/8+.....+x:512=511

2x+4x+8x+.....+512x=511

x(2+4+8+........+512)=511

x(2^1+2^2+2^3+......+2^9)=511

Gọi S=2^1+2^2+2^3+.....+2^9

2S-S=(2^2+2^3+2^4+.....+2^10)-(2^1+2^2+2^3+......+2^9)

S=2^10-2

x(2^10-2)=511

2x(2^9-1)=511

2x(512-1)=511

2x.511=511

2x=1

x=1/2

Vậy x=1/2

Chúc bạn học tốt^^

Answer 4

Cảm ơn mọi người nhiều nha.Tại đề bị lỗi thôi

Answer 5

879654321 -12345678990987542

 

Answer 6

$x:\frac{1}{2}+x:\frac{1}{4}+x:\frac{1}{8}+...+x:\frac{1}{512}=511$

$x.2+x.4+x.8+...+x.512=511$

$x.\left(2+4+8+...+512\right)=511$

$x.65792=511$

x=511:65792

                $x=\frac{511}{65792}$

Answer 7

x : 1/2 + x : 1/4 + x : 1/8  + ... + x : 1/512 = 511

=> 2x + 4x + 8x + ... + 512x = 511

=> x(2 + 4 + 8 + ... + 512) = 511

=> 65792x = 511

=> x = 511/65792

Answer 8

x*2+x*4+x*8+...=x*512=511

x*(2+4+8+...+512)=511

x*1022=511

x=511:1022

x=1/2