recursive formula: pn= (1+r)pn-1  explicit formula: pn= (1+r)^n (po)  r= rate of change
recursive formula: pn= (1+r)pn-1  explicit formula: pn= (1+r)^n (po)  r= rate of change
1. initial quantity of something starts to grow and the rate of growth increases - mathematical model - more often, sales follow s curve