Question

[linh nguyễn]

cho A=\(\frac{1+2+2^2+2^3+2^4+...+2^{2018}}{2^{2019}}\)    so sánh A với 1

Answer 1

[Trương Nguyễn Tú Anh]

2A = 2+ 2^2+.......+2^2018+ 2^2019 / 2 ^2019 

2A-A = 2+2^2+.....+2^2019/ 2^2019 - 1=2+....+2^2018/ 2^2019 

A =2^2019-1 / 2^2019 < 1 

suy A< 1

Answer 2

[Trương Nguyễn Tú Anh]

xin lỗi mình hơi nhầm : 2A - A = 2+2^2+....+2^2019/2^2019- 1+2+2^2 +.....+2^2019/2^2019