Question

3^x-1 + 3^x + 3^{x+1 = 39}

Answer 1

\(\Leftrightarrow3^x\left(\dfrac{1}{3}+1+3\right)=39\)

\(\Leftrightarrow3^x=39:\dfrac{13}{3}=39\cdot\dfrac{3}{13}=9\)

=>x=2

Answer 2

`3^(x-1) +3^x +3^(x+1)=39`

`3^x  : 3^1 +3^x + 3^x.3^1=39`

`3^x . 1/3 +3^x + 3^x.3^1=39`

`3^x . (1/3+1+3)=39`

`3^x . 13/3 =39`

`3^x=39:13/3`

`3^x = 9`