Question

Consider the sequence below.

3 , 1 , 1/3 , 1/9 , ...

Select the explicit function which defines the sequence.

Answer 1

As we can see it's a geometric progression.

q = a2/a1

q = 1/3

so,

an = a1 . q^(n - 1)

an = 3 . (1/3)^(n - 1)

The one which matches is f(n) = 3 . (1/3)^(n - 1)

Alt C.