[tex]Se~considera~sirul ~(a_{n}),astfel ~incat~a_{1}=2~si~a_{n+1}=3*a_{n}+2 \\ Sa~se~determine~a_{n}~stiind~ca~exista~ \alpha \in R~astfel~incat~ \\ sirul~(b_{n}),b_{n}=a_{n}+ \alpha ~este~progresie~geo.[/tex]