Question

The formula f(x + 1) = Two-thirds(f(x)) defines a geometric sequence where f(1) = 18. Which explicit formula can be used to model the same sequence?

Answer 1

f(x) = 18*(2/3)^(x-1), for x = 1, 2, 3, ...

(Each step multiplies by 2/3, and at x=1 the value is 18.)