Don has been tracking the population of a town. The population was 7,220 last year and has been increasing by 1.45 times each year. How can Don develop a function to model this?

f(x) = (7220 ⋅ 1.45)x where 1.45 is the rate of growth
f(x) = 1.45(7220)x where 7220 is the rate of growth
f(x) = 7220(1.45)x where 1.45 is the rate of growth
f(x) = 7220(x)1.45 where 7220 is the rate of growth