Arithmetic sequences have a common difference between consecutive terms.
Geometric sequences have a common ratio between consecutive terms.
Let's compute the differences and ratios between consecutive terms:
Differences:
Ratios:
So, as you can see, the differences between consecutive terms are constant, whereas ratios vary.
So, this is an arithmetic sequence.
I'm assuming you're referring to problem 6. You are asked to find the number of x intercepts or roots, which is another term for "zero". I prefer the term root or x intercept as "zero" seems misleading. Anyways, all we do is count the number of times the graph crosses the x axis. This happens 4 times as shown in the attached image below. I have marked these points in red. The graph can directly cross over the x axis, or it can touch the x axis and then bounce back. Either way, it is considered an x intercept.
<h3>Answer: there are 4 x intercepts (or 4 roots)</h3>
