4) \(2.3^x+3^{x-1}=7.\left(3^2+2.6^2\right)\)
\(\Rightarrow2.3^x+3^{x-1}=567\)
\(\Rightarrow7.3^{x-1}=567\)
\(\Rightarrow3^{x-1}=567\div7\)
\(\Rightarrow3^{x-1}=81\)
\(\Rightarrow3^{x-1}=3^4\)
\(\Rightarrow x-1=4\)
\(\Rightarrow x=4+1\)
\(\Rightarrow x=5\)
Vậy \(x=5\)