Question

What is the explicit rule for the sequence?

Answer 1

ANSWER

The explicit rule for the sequence is

$a_n=18+2.5n$


EXPLANATION

The terms of the sequence are
$15.5,13,10.5,8,5.5,3,...$


The first term of the sequence is
$a = 15.5$
and the constant difference is
$d =13 - 15.5 = - 2.5$
Since there is a constant difference, it means the sequence is an arithmetic progression.



The general formula for an arithmetic sequence is given by the formula,


$a_n=a+(n-1)d$





We substitute the above values to obtain,



$a_n=15.5 - 2.5(n-1)$



We expand to obtain,


$a_n=15.5 - 2.5n + 2.5$


This will simplify to,

$a_n=18+2.5n$


Therefore the correct answer is A.

Answer 2

Hello, sorry this is a little late!

I believe the correct answer to your question would best be Option A.

I can confirm this is 100% correct!

Hope this helps and have a great rest of your day :)