Answer:
B), C) and D)
Step-by-step explanation:
A geometric sequence is the sequence in which the ratio between any two consecutive terms a constant. It is represented by "r".
Common ratio = Second term /First term
The general forma of a geometric sequence is a. ar. a^2.......ar^n.
Let's find the common ratio.
A. 4/1 = 4 ; 9/4 = 2.25
The common ratio is not the same through out the sequence. Therefore, it is not a geometric sequence.
B. 5/10 = 1/2 ; 2.5/5 = 1/2 ; 1.25/2.5 = 1/2
The common ratio is the same through the sequence. Therefore it is a geometric sequence.
C. 1, 2, 4, 8,16, 32
Common ratio = 2/1 = 2
4/2 = 2; 8/4 = 2
The common ratio is the same through the sequence. Therefore it is a geometric sequence.
D. 2, -2, 2, -2, 2, -2
The common ratio = -2/2 = -1
-2/2 = -1
So here a = 2 and r = -1
The common ratio is the same through the sequence. Therefore it is a geometric sequence.
Therefore, answer is B), C) and D)
