To classify the given list of numbers: 9, 4, −1, −6, let's first check if it is an arithmetic or geometric sequence.
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Arithmetic Sequence: An arithmetic sequence has a constant difference between consecutive terms.
- The difference between the first two terms: 4 - 9 = -5
- The difference between the second and third terms: -1 - 4 = -5
- The difference between the third and fourth terms: -6 - (-1) = -5
Since the difference is constant (-5) for all consecutive terms, this is an arithmetic sequence.
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Geometric Sequence: A geometric sequence has a constant ratio between consecutive terms. We can quickly see that the ratios are not constant since:
- The ratio of the first two terms is 4 / 9 (not a simple, consistent ratio).
- Hence, it is not a geometric sequence.
Based on the above examination, the correct classification of the sequence 9, 4, −1, −6 is arithmetic sequence.