Question

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

Answer 1

7.5

Explanation:

Answer 2

f(n+1)=-1/2f(n)
f(n)=-2f(n+1)
given f(1)=120
-2f(1+1)=120
f(2)=-60
f(2)=-2f(2+1)=-60
f(3)=30
f(3)=-2f(3+1)=30
f(4)=-15
f(4)=-2f(4+1)=-15
f(5)=15/2