Question

state whether the following sequence is an arithmetic or not 3,6,12,24

Answer 1

3,6,12,24,.....

We note that the constance term is r= 2

a1= 3

a2= 3*r = 3*2 = 6

A3= 3*r^2 = 3*2^2 = 3*4 = 12

a4 = 3*r^3 = 3*8 = 24


a9= 3*r^8 = 3*2^8 = 3*256 = 768

an = 3^r^(n-1)= 3*2^(n-1)

Answer 2

3,6,12,12
let d=3
d1=6
d2=12
d3=24
d=3,difference a=d1-d=6-3=3
a=d2-d1=12-6=6
as
d1-d is not equal to d2-d1
so they are not in form of AP