Question

Tính:

B=1-1/2+1/4-1/8+1/16-...+1/1024

Answer 1

B x 2 = 1 - ( 1/2 + 1/4 + 1/8 + 1/16 + ..... + 1/512 + 1/1024 ) - 1/1024

B x 2 = 1 - 1/1024 + A

B x 2 - B = 1 - 1/1024

B = 1 - 1/1024

B = 1023 /1024

Answer 2

làm lại bài kia sai 1 chỗ 

\(B=1-\frac{1}{2}+\frac{1}{4}-\frac{1}{8}+\frac{1}{16}-...+\frac{1}{1024}\)

\(\Rightarrow Bx2=1-\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{1024}\right)-\frac{1}{1024}\)

\(\Rightarrow Bx2=1-\frac{1}{1024}+B\)

\(\Rightarrow Bx2-B=1-\frac{1}{1024}\)

\(\Rightarrow B=\frac{1023}{1024}\)

Answer 3

Cảm ơn Biển Ác Ma