Question

1/2+1/4+1/8+1/16+1/32

Ko đc quy đồng nha! 

Answer 1

nếu k quy đồng olaf k tính đc bn nhé

Answer 2

\(\text{Đặt A = }\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}\)

\(2\text{A}=1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}\)

\(2\text{A}-\text{A}=\left(1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}\right)-\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}\right)\)

\(\text{A}=1-\frac{1}{32}=\frac{31}{32}\)

Answer 3

Đặt A = 1/2+1/4+1/8+1/16+1/32

=> 2A = 1 + 1/2+1/4+1/8+1/16

=> 2A - A = 1 - 1/32

=> A = 31/32

Answer 4

\(\text{Đặt A = }\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}\)

\(2\text{A}=1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}\)

\(2\text{A}-\text{A}=\left(1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}\right)-\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}\right)\)

\(\text{A}=1-\frac{1}{32}=\frac{31}{32}\)