Answer:
D. an = 4n
Explanation:
The formula for finding a term of an arithmetic sequence is:
an = a1 + (n-1)d
where an is the nth term, a1 is the first term and d is the common difference between the terms.
To find d we can take any two adjacent terms and subtract one from the other. e.g. 8 - 4 = 4, 16-12 = 4 etc.
The common difference here is 4, and we can see that the first term of the sequence is also 4, therefore our formula now looks like this:
an = 4 + (n-1)4
Now we can just expand out the brackets to find the final answer:
an = 4 + 4n - 4
an = 4n
Hope this helped!