Question

On a coordinate plane, 3 points are plotted. The points are (1, 80), (2, 20), (3, 5).
Which function can be used to represent the graphed geometric sequence?

Answer 1

The common ratio is 20/80 = 5/20 = 1/4, so the nth-term form is
y = 80*(1/4)^(x-1).

(Equivalently y = 320*(1/4)^x.)