what is the correct function for the geometric sequence 5, 2.5, 1.25, 0.625?

Answer 1

2.5 / 5 = 1.25 / 2.5 = 0.625 / 1.25 = 1/2

The sequence is geometric with common ratio r = 1/2

a_n = nth term of the sequence = 5(1/2)^n-1

Or, we can write f(n) = 5(1/2)^n-1