Answer: Choice B) First is geometric. Second is arithmetic.
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For the sequence {2, 14, 98, 686, ...} we start off with 2 and multiply that by 7 to get the next term (14) and then multiply that by 7 to get the term after that (98) and so on. The common ratio is 7. We can see this by dividing any term by its previous one. For example, 98/14 = 7.
The sequence {-5, -10, -15, -20, ...} is arithmetic because we subtract 5 each time to generate the next term. This is the same as adding -5 each time. Therefore the common difference is -5. To find the common difference, pick any term you want and subtract off the previous term. Example: -15 - (-10) = -15+10 = -5.
