Question

A sequence is defined recursively using the formula . If the first term of the sequence is 120, what is f(5)?

−15
−7.5
7.5
15


What is the common ratio between successive terms in the sequence?

1.5, 1.2, 0.96, 0.768, …

–0.8
–0.3
0.3
0.8

What is the common ratio between successive terms in the sequence?

1.5, 1.2, 0.96, 0.768, …

–0.8
–0.3
0.3
0.8

Answer 1

1) f(5) = 7.5
Reason: f(5) = 120·r^4 and r^4 must be 7.5/120 = 1/16 → f(5)=7.5.

2) Common ratio = 0.8
(1.2/1.5 = 0.8, 0.96/1.2 = 0.8, 0.768/0.96 = 0.8)

(Second repeated question same answer: 0.8.)