Question

Which of the following are geometric sequences?

Check all that apply.
A. 5, 10, 15, 20, 25
B. 10, 5, 2.5, 1.25, 0.625, 0.3125
C. 1, 1, 2, 3, 5, 8, 13
D. -9, -3, -1, -1/3, -1/9, -1/27

Answer 1

Answer: B and D

Explanation:

A is not, it's an arithmetic sequence where each term is +5 greater than the previous

B is because each term is 1/2 the previous term (common ratio of 1/2) thus making it a geometric sequence

C is not, it's the Fibonnaci sequence which is neither an arithmetic or geometric sequence

D is because each term is 1/3 the previous term (common ratio of 1/3) thus making it a geometric sequence