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Which of these is a geometric sequence?

A. 3, -15, -33, -51, -69, ...
B. 2, 3, 5, 9, 17, ...
C. 1,5, 9, 13, ..
D. 1/4, 1/2, 1, 2, 4

User Propstm
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1 Answer

3 votes

Final answer:

Option D (1/4, 1/2, 1, 2, 4) is the geometric sequence as there is a consistent common ratio of 2 between consecutive terms.

Step-by-step explanation:

To identify which of the given sequences is a geometric sequence, we need to look for a consistent ratio between consecutive terms. Here's how we examine each option:

  • A. 3, -15, -33, -51, -69, ... does not have a common ratio. The differences are not consistent, and it's not multiplying by a common factor.
  • B. 2, 3, 5, 9, 17, ... also does not have a common ratio; these numbers do not fit the pattern of a geometric sequence as they are not formed by multiplying the previous term by a fixed number.
  • C. 1, 5, 9, 13, ... is an arithmetic sequence, not a geometric one, since each term is obtained by adding a common difference.
  • D. 1/4, 1/2, 1, 2, 4 is a geometric sequence. Each term is obtained by multiplying the previous term by the common ratio of 2.

Therefore, the correct answer is D. 1/4, 1/2, 1, 2, 4, which clearly shows a common ratio of 2 between each term in the sequence.

User Avinash Solanki
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