Question

1.Rút gọn

a) C = 1/2 + 1/2^2 + 1/2^3 + ....+ 1/2^2020

Answer 1

Giải:

C=1/2 + 1/2^2 + 1/2^3 + ... + 1/2^2020

2C=1 + 1/2 + 1/2^2 + ... +1/2^2019

2C-C=(1+1/2+1/2^2+...+1/2^2019)-(1/2+1/2^2+1/2^3+...+1/2^2020)

C=1-1/2^2020

Chúc bạn học tốt!