Answer the questions about the sequence below.

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Is the sequence arithmetic or geometric?
Does it have a common difference or common ratio?
What is the common difference or common ratio?
What are the next three terms?


256, 64, 16, 4, 1, . . .

1 answer

To determine whether the sequence is arithmetic or geometric, we can analyze the relationship between consecutive terms.

  1. Identify the type of sequence:
    • A sequence is arithmetic if the difference between consecutive terms is constant (called the common difference).
    • A sequence is geometric if the ratio between consecutive terms is constant (called the common ratio).

Let's look at the given sequence: 256, 64, 16, 4, 1.

  1. Calculate the ratios between consecutive terms:
    • From 256 to 64: \( \frac{64}{256} = \frac{1}{4} \)
    • From 64 to 16: \( \frac{16}{64} = \frac{1}{4} \)
    • From 16 to 4: \( \frac{4}{16} = \frac{1}{4} \)
    • From 4 to 1: \( \frac{1}{4} = \frac{1}{4} \)

Since the ratio between each pair of consecutive terms is constant and equal to \( \frac{1}{4} \), this indicates that the sequence is geometric.

  1. Common ratio: The common ratio (r) of this geometric sequence is \( \frac{1}{4} \).

  2. Next three terms: To find the next terms in the sequence, we can continue multiplying the last term by the common ratio:

  • The next term after 1: \( 1 \times \frac{1}{4} = \frac{1}{4} \)

  • The term after \( \frac{1}{4} \): \( \frac{1}{4} \times \frac{1}{4} = \frac{1}{16} \)

  • The term after \( \frac{1}{16} \): \( \frac{1}{16} \times \frac{1}{4} = \frac{1}{64} \)

Thus, the next three terms are \( \frac{1}{4}, \frac{1}{16}, \) and \( \frac{1}{64} \).

Summary:

  • The sequence is geometric.
  • It has a common ratio.
  • The common ratio is \( \frac{1}{4} \).
  • The next three terms are \( \frac{1}{4}, \frac{1}{16}, \frac{1}{64} \).