Question

[Âu Nguyễn Bảo Châu]

Tính nhanh tổng sau:

B= 1/2 + 1/4 + 1/8 +  1/16 + 1/32 + 1/64

Answer 1

[Nguyễn Duy Sơn]

dề có sai ko

Answer 2

[Laura]

B= 1/2 + 1/4 + 1/8 +  1/16 + 1/32 + 1/64

B=1/2+1/2^2+1/2^3+1/2^4+1/2^5+1/2^6

=>2B=1+1/2+1/2^2+...1/3^5

=>2B-B=1-1/2^6

=>B=1-1/64

=>B=63/64