An arithmetic sequence has a common difference between each term in the series. A geometric sequence has a common ratio between each term in the series.
First, let's determine the rate of change between each term.
10, 20 = multiplied by 2
20, 40 = multiplied by 2
40, 80 = multiplied by 2
The terms appear to have a common ratio of 2, making this a geometric sequence. Therefore, this is NOT an arithmetic sequence.
