Question

A sequence is defined recursively using the equation formula f(n+1) = -0.5 f(n). If the first term of the sequence is 120, what is f(5)?

Answer 1

f(5) = 7.5

Explanation:

given the recursive formula, then the next term in the sequence can be found from the previous term, that is

f(2) = - 0.5 × f(1) = - 0.5 × 120 = - 60

f(3) = - 0.5 × f(2) = - 0.5 × - 60 = 30

f(4) = - 0.5 × f(3) = - 0.5 × 30 = - 15

f(5) = - 0.5 × f(4) = - 0.5 × - 15 = 7.5