Respuesta :

I start with 1 friend on Facebook. Every month I find that the number of friends I have triples. 

Month 0 --> y = 3^0 = 1 friend 
Month 1 --> y = 3^1 = 3 friends 
Month 2 --> y = 3^2 = 9 friends 
Month 3 --> y = 3^3 = 27 friends 
... 
Month t --> y = 3^t