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**Answer: Choice B) -3, 3, -3, 3, ....**</h3>

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How I got that answer:

A sequence is geometric if you are able to divide any term over its prior one and get the same result each time. Note with something like choice A we have...

term2/term1 = 13/6 = 2.17 (approx) and term3/term2 = 19/13 = 1.46

the results 2.17 and 1.46 are not the same, so we can rule out choice A

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Choice B however, we have...

term2/term1 = 3/(-3) = -1

term3/term2 = -3/3 = -1

term4/term3 = 3/(-3) = -1

each time we get -1, so this is the common ratio. We can multiply each term by the common ratio -1 to get the next term, for instance,

term2 = (common ratio)*(term1) = -1*(-3) = 3

term3 = (common ratio)*(term2) = -1*3 = -3

and so on. This proves that sequence B is geometric. Sequences C and D are not geometric for similar reasoning to choice A.