How do you determine whether the sequence $5, 15, 45, 135,...$ is geometric and if it is, what is the common ratio?

Question

23002 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2017-05-09T11:47:18

Common ratio is $3$

Sequence : $5, 15, 45, 135,.......$

$a_1=5 , a_2=15, a_3=45 , a_4=135, .......$

$a_2/a_1= 15/5 =3 , a_3/a_2= 45/15 =3 , a_4/a_3= 135/45 =3 , .....$

In this sequence the ratio of each term and the previous term is

constant , so it is geometric sequnce and constant is $3$ .

Common ratio is $3$ [Ans]

How do you determine whether the sequence 5, 15, 45, 135,...5, 15, 45, 135,... is geometric and if it is, what is the common ratio?