Question

A sequence is defined by the recursive function f(n + 1) = f(n). If f(3) = 9 , what is f(1) ?

Answer 1

Assuming that f(n+1) = f(n) is the full recursive definition, and that there are no typos, then this means that the nth term is equal to the (n+1)th term for any n where n is a positive whole number.

So
f(1) = f(2)
f(2) = f(3)
f(3) = 9

By the transitive property, f(1) = f(3) = 9. Therefore the answer is 9.