Answer :
\(\Rightarrow A+1=1+1+2+2^2+...+2^{2021}\)
\(\Rightarrow A+1=2+2+2^2+...+2^{2021}\)
\(\Rightarrow A+1=2^2+2^2+2^3+...+2^{2021}\)
\(\Rightarrow A+1=2^3+2^3+2^4+...+2^{2021}\)
....
\(\Rightarrow A+1=2^{2021}+2^{2021}=2^{2022}\)
Mà \(2^x=A+1\Rightarrow2^x=2^{2022}\Rightarrow x=2022\)