Answer
The sequence is arithmetic.
Common difference: $d=3.5$.
General term: $a_{n}=3.5n-8.5$
Work Step by Step
$-1.5-(-5)=2-(-1.5)=5.5-2=9-5.5=12.5-9=3.5$
We see that the difference between each term and the preceding term is same and is equal to $3.5$.
Therefore, the sequence is arithmetic with common difference $d=3.5$.
The general term $a_{n}$ is given by
$a_{n}=a_{1}+(n-1)d$
As $a_1=-5$ and $d=3.5$, we have:
$a_{n}=-5+(n-1)3.5=-5+3.5n-3.5$
$a_{n}=3.5n-8.5$
