\(7^{2x}+7^{2x+3}=344\\ 7^{2x}\left(1+343\right)=344\\ 7^{2x}.344=344\\ 7^{2x}=1\\ 2x=0\\ x=0\)
Vậy x = 0
Ta có: \(7^{2x}+7^{2x+3}=344\)
\(\Leftrightarrow7^{2x}+7^{2x}\cdot7^3=344\)
\(\Leftrightarrow7^{2x}\left(1+7^3\right)=344\)
\(\Leftrightarrow7^{2x}=1\)
\(\Leftrightarrow2x=0\)
Vì 2>0
nên x=0
Vậy: x=0