Question

Sa se rezolve in multimea R ecuatia: $3^{x+2}$ + $3^{x+1}$ + $3^{x}$ =39

Answer 1

$3^{x+2}+ 3^{x+1}+ 3^{x}=39$

$3^{x}* 3^{2}+ 3^{x}*3+ 3^{x}=39$

$3^{x}( 3^{2}+3+1)=39$

$3^{x}*13=39$

$3^{x}=39:13$

$3^{x}=3$

$x=1$