Question

1/3+1/6+1/12+1/24+1/48+1/96+1/142

Answer 1

Sửa đề: \(A=\dfrac{1}{3}+\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{24}+\dfrac{1}{48}+\dfrac{1}{96}+\dfrac{1}{192}\)

=1/3(1+1/2+1/4+...+1/64)

Đặt B=1+1/2+1/4+...+1/64

=>2B=2+1+...+1/32

=>B=1-1/64=63/64

=>A=1/3*63/64=21/64