Hello from MrBillDoesMath!
Answer:
f(x) = 8 * 3^x
Discussion:
x = 0: f(x) = 8
x = 1: f(1) = f(0) * 3 = 8*3
x = 2: f(2) = f(2-1)*3 = f(1) * 3 = (8*3)*3 = 8 * 3^2
x=3 : f(3) = f(3-1)*3 = f(2)*3 = (8 * 3^2) * 3 = 8 * 3^3
Based on this we guess that
f(x) = 8 * 3^x
Thank you,
MrB