Progresie geometrica->
b2= b1*r (r=ratia)
b3= b2*r=b1*r*r=b1*r^2 [^=ridicare la putere)
Dar avem ca b2-b1=b1*(r-1)=2
b3-b1=b1(r^2-1)=b1(r-1)(r+1)=8
Impartim cele 2 relatii si avem
r+1=8/2=4 r=3
Inlocuim in prima relatie
b1(3-1)=2 b1=1
b2018=b1*r^2017=2^2017
