\(3^{x+2}-3^x=24\)
\(\Leftrightarrow3^x\left(3^2-1\right)=24\)
\(\Leftrightarrow3^x.8=24\)
\(\Leftrightarrow3^x=3\)
\(\Rightarrow x=1\)
\(3^{x+2}-3^x=24\)
\(3^x.3^2-3^x=24\)
\(3^x\left(9-1\right)=24\)
\(3^x.8=24\)
\(3^x=\dfrac{24}{8}\)
\(3^x=3^1\)
\(\Leftrightarrow x=1\)
Vậy x=1