What is the arithmetic sequence in this problem

a(n)=80*(9/10)^(n-1)

Step-by-step explanation:

I think u r confused

this sequence is geometric not arithmetic

HOw we know that ??

when we get a common difference  that must Be equal  

d=72-80=-8  not equal to  d=64.8-72=-7.2

So it is not arithmetic

but when we get the common ratio that also must be equal

r=72/80=9/10 equal to   r=64.8/72=9/10

So it is geometric

By using this equation:

a(n)=a*r^(n-1)

and we have a=80 , r=9/10

Then       a(n)=80*(9/10)^(n-1)

I really hope this helps <3

if you use photomath right away it will give you the answer not like this app that you have to wait for people.

6/20

step-by-step explanation: