Question

Cho S = 1+ 2+ 2²+ 2³+...+2²⁰⁰⁵ 

So sánh S với 5.2²⁰⁰⁴

Answer 1

đáp án https://goo.gl/BjYiDy

Answer 2

Ta có: \(S=1+2+2^2+...+2^{2005}\)

         \(2S=2\left(1+2+2^2+...+2^{2005}\right)\)

          \(2S-S=\left(2+2^2+2^3+...+2^{2005}+2^{2006}\right)\)\(-\left(1+2+2^2+...+2^{2005}\right)\)

           \(S=2^{2006}-1\)

Mà \(5.2^{2004}=\left(1+2^2\right)\)=