Question

Determine if the sequence below is arithmetic or geometric and determine the

common difference / ratio in simplest form.
5, 15, 45, ...

Answer 1

a1=5
a2=15
a3=45
a2/a1=15/5=3
a3/a4=45/15=3
Sequence is geometric-the ration of each term and previous term is CONSTANT. Ratio is: 3
There is no common difference (d), as sequins not arithmetic.

d=a(n) - a(n-1)
a(n) is last term
a(n-1) is the previous term
d=45-15
d=30
d=15-5=10
The difference between each number in sequence is not the same therefore, there is not common difference.

Good luck.