Answer
The sequence is arithmetic.
Common difference: $d=1.25$.
General term: $a_{n}=1.25n+2.75$
Work Step by Step
$5.25-4=6.5-5.25=7.75-6.5=9-7.75=10.25-9=1.25$
We see that the difference between each term and the preceding term is same and is equal to $1.25$.
Therefore, the sequence is arithmetic with common difference $d=1.25$.
The general term $a_{n}$ is given by
$a_{n}=a_{1}+(n-1)d$
As $a_1=4$ and $d=1.25$, we have:
$a_{n}=4+(n-1)1.25=4+1.25n-1.25$
$a_{n}=1.25n+2.75$
