Question

2, 1, 1/2, 1/4...

a. arithmetic
b. geometric
c. both
d. neither

Is it d? Thanks!

Answer 1

Or is it b...

Answer 2

b is right. Each number is 1/2 of the previous number.

Answer 3

Thanks you, Ms. Sue. You're sure are a great help.

Answer 4

You are welcome, Chrisley. :-)

Answer 5

Actually, all the answers given (a, b, c, d) are wrong.
The correct answer should be
e. CANNOT BE DETERMINED

For a, an arithmetic sequence refers to a sequence that the difference between consecutive terms ((n+1)th term - nth term) is constant. Obviously 1-2 =/= 1/2-1
a is wrong
Thus, c is wrong.

For b, a geometric sequence refers to a sequence that the ratio between consecutive terms i.e. (n+1)th term/nth term is constant. Although the given four terms, such ratio is constant, i.e. 1/2=1/2/1=1/4 / 1/2, the fifth term is not given and you cannot know the general term of the sequence and thus the GENERAL ratio of the sequence.
So, it CANNOT be determined if b is correct if the GENERAL TERM of the sequence is NOT GIVEN and so as d.

Therefore, the answer is e, i.e. CANNOT BE DETERMINED.
(Point to note: You can ONLY determine if a sequence is arithmetic or geometric by knowing its GENERAL TERM and test if the common difference or ratio is CONSTANT.