Answer:
geometric, 1/4
Step-by-step explanation:
An arithmetic sequence will have a common difference. A geometric sequence will have a common ratio. If neither of those describes the sequence, it is "neither."
Obviously the difference between numbers in this sequence is decreasing, so this is not an arithmetic sequence.
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The ratios of adjacent terms are ...
-320/-1280 = -80/-320 = -20/-80 = -5/-20 = 1/4
The sequence is a geometric sequence with a common ratio of 1/4.