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

2A=1+1/2+1/4+1/8...1/256

A=(1+1/2+1/4+1/8...1/256)-(1/2+1/4+1/8.....+1/256+1/512)

A=1-1/512

A=511/512

511/512

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

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

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

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

\(x.65792=511\)

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

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^^

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

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

=> x . 2 + x . 2² + x . 2³ + ... + x . 2⁹ = 511

=> x . (2 + 2² + 2³ + ... + 2⁹) = 511

=> x . 1022 = 511

=> x = 511 : 1022

=> x = 1/2 (Loại)

Vậy x thuộc rỗng.

Tính sai rồi bạn ơi 2+2^2+2^3+.....+2^9 ko phải bằng 1022

1022 đúng rồi mà

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