\(3^x+3^{x-2}=810\)
<=> \(3^x+3^x:3^2=810\)
<=> \(3^x\left(1+\frac{1}{9}\right)=810\)
<=> \(3^x=729\)
<=>\(3^x=3^6\)
=> x=6
3x +3x-2 = 810
\(\Rightarrow3^x\left(1+3^{-2}\right)=810\)
\(\Rightarrow3^x\left(1+\frac{1}{3^2}\right)=810\)
\(\Rightarrow3^x\left(1+\frac{1}{9}\right)=810\)
\(\Rightarrow3^x\cdot\frac{10}{9}=810\)
\(\Rightarrow3^x=729\)
\(\Rightarrow3^x=3^6\Leftrightarrow x=6\)
\(3^x+3^{x+2}=810\)
\(=>3^x+3^x:3^2=810\)
\(=>3^x.\left(1+\frac{1}{9}\right)=810\)
\(=>3^x.\frac{10}{9}=810\)
\(=>3^x=729\)
\(=>3^x=3^6\)
\(< =>x=6\)
