Answer:
f(n)= 5 · 4
[tex]f(n) = 5 \times 4 ^{n - 1} [/tex]
Step-by-step explanation:
You use the explicit formula for geometric sequence. The five is the firat term and is placed correctly. The 4 is the rate of change, because if you multiply 5 by 4 you get 20 and so on.
