$\text{$3^{2x}$ + $3^{x}$ + 3 = 759}$
$\text{$3^{x}$.$3^{x}$ + $3^{x}$ + 3 = 759}$
$\text{$3^{x}$.$3^{x}$ + $3^{x}$ = 759 - 3}$
$\text{$3^{x}$.$3^{x}$ + $3^{x}$ = 756}$
$\text{$3^{x}$ ($3^{x + 1}$) = 756}$
$\text{$3^{x}$ ($3^{x + 1}$) = 27.28}$
$\text{=> $3^{x}$ = 27}$
$\text{ $3^{x}$ = $3^{3}$}$
$\text{=> x = 3}$