3x+3x+2=810
\(3^x\).1 + \(3^x\).\(3^2\) =810
\(3^x\) .(1 + \(3^2\) )=810
\(3^x\) .10 =810
\(3^x\) =810 :10
\(3^x\) = 81
\(3^x\) =\(3^4\)
\(\Rightarrow\) 4
Vậy x=4
\(3^x+3^{x+2}=810\)
\(\Rightarrow3^x+3^x.3^2=810\)
\(\Rightarrow3^x.\left(1+3^2\right)=810\)
\(\Rightarrow3^x.10=810\)
\(\Rightarrow3^x=81\)
\(\Rightarrow3^x=3^4\)
\(\Rightarrow x=4\)
Vậy \(x=4\)
\(3^x+3^{x+2}=810\)
\(3^x.1+3^x.3^2=810\)
\(3^x.\left(1+3^2\right)\) \(=810\)
\(3^x.10=810\)
\(3^x=810:10\)
\(3^x=81\)
\(3^x=3^4\)
\(\Rightarrow x=4\)
Vậy \(x=4\)
