Question

Cho Khi đó
Vậy

Answer 1

\(S=1-2+2^2-2^3+...+2^{2013}-2^{2014}\)

\(2S=2\left(1-2+2^2-2^3+...+2^{2013}-2^{2014}\right)\)

\(2S=2-2^2+2^3-2^4+...+2^{2014}-2^{2015}\)

\(2S+S=\left(2-2^2+...+2^{2014}-2^{2015}\right)+\left(1-2+...+2^{2013}-2^{2014}\right)\)

\(3S=2^{2015}+1\). Khi đó \(1-3S=2^x\Leftrightarrow1-2^{2015}+1=2^x\)

\(\Leftrightarrow2^{2015}=2^x\Leftrightarrow x=2015\)

Answer 2

x=2015 đúng ko

ko ranh nên ko viết hết ra đc