Question

Which sequence is NOT a geometric progression?
A) 3, 6, 9, 12
B) 1, 5, 25, 125
C) 4, 8, 16, 32
D) 2, 6, 18, 54

Answer 1

Hey there! Thanks for the question!

Geometric progression is a progression where the consecutive terms of the series have a constant ratio.

Let, a, b , c be the Three terms of geometric progression then b/a =c/b .

Now,
Checking the First option,

A) 12/9 = 9/6 = 6/3

4/3 ≠ 3/2 ≠2/1

Not a geometric progression, as they don't have a constant ratio.

B) 125 / 25 = 25/5 = 5/1

5 = 5 = 5

Is a geometric progression, because it has a constant ratio.

C) 4 , 8 , 16 , 32

32/16 = 16/8 = 8/4

2 = 2 = 2

D) 2 , 6 , 18 , 54

54/18 = 18/6 = 6/2

3 = 3 = 3 .

These are geometric progressions , because they have a constant ratio.

So, 3 , 6 , 9 , 12 is not a Geometric progression, but an Arithmetic progression

Option ( A ) is correct

Answer 2

Option ( A ) is correct