Question

so sánh 

a)A=1/2^1+1/2^2+1/2^3+...+1/2^49+1/2^50 với 1

b)B=1/3^1 +1/3^2+1/3^3...+1/3^99+1/3^100 với 1/2

c)C=1/4^1+1/4^2+1/4^3+...+1/4^999+1/4^1000 với 1/3

Answer 1

a)\(A=\frac{1}{2^1}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{49}}+\frac{1}{2^{50}}\)

\(2A=1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^{48}}+\frac{1}{2^{49}}\)

\(A=1-\frac{1}{2^{50}}

Answer 2

Bạn Detective_conan giải đúng đấy!