๐Ÿ“honors pre-calculus review

Constant Sequence

Written by the Fiveable Content Team โ€ข Last updated September 2025
Written by the Fiveable Content Team โ€ข Last updated September 2025

Definition

A constant sequence is a special type of sequence where each term is the same value. In other words, the difference between any two consecutive terms is zero, making the sequence constant or unchanging.

5 Must Know Facts For Your Next Test

  1. The general formula for a constant sequence is $a_n = a$, where $a$ is the constant value and $n$ is the term number.
  2. Constant sequences have a common difference of 0, meaning the difference between any two consecutive terms is always 0.
  3. Constant sequences can be thought of as a special case of arithmetic sequences, where the common difference is 0.
  4. The sum of the terms in a constant sequence can be calculated using the formula $S_n = na$, where $S_n$ is the sum of the first $n$ terms and $a$ is the constant value.
  5. Constant sequences are often used to model situations where a quantity remains unchanged over time, such as a fixed interest rate or a constant population size.

Review Questions

  • Explain how a constant sequence differs from an arithmetic sequence.
    • The key difference between a constant sequence and an arithmetic sequence is the common difference between terms. In a constant sequence, the common difference is always 0, meaning each term is the same value. In an arithmetic sequence, the common difference is a non-zero constant, resulting in a sequence where the terms increase or decrease by a fixed amount. Constant sequences can be considered a special case of arithmetic sequences where the common difference is 0.
  • Describe how the formula for the sum of the terms in a constant sequence differs from the formula for the sum of the terms in an arithmetic sequence.
    • The formula for the sum of the first $n$ terms in a constant sequence is $S_n = na$, where $a$ is the constant value. This is different from the formula for the sum of the first $n$ terms in an arithmetic sequence, which is $S_n = \frac{n}{2}[2a_1 + (n-1)d]$, where $a_1$ is the first term and $d$ is the common difference. The constant sequence formula is simpler because the common difference is 0, whereas the arithmetic sequence formula accounts for the non-zero common difference.
  • Analyze how the properties of a constant sequence, such as the common difference and the formula for the sum of the terms, can be used to model real-world situations.
    • Constant sequences can be used to model real-world situations where a quantity remains fixed or unchanged over time. For example, the monthly rent payment for a apartment, the interest rate on a savings account, or the population of a species in a stable environment can all be represented by constant sequences. The properties of a constant sequence, such as the common difference of 0 and the simple formula for the sum of the terms, make it a useful tool for analyzing and predicting the behavior of these types of situations. By understanding the characteristics of constant sequences, we can better understand and make inferences about the real-world phenomena they represent.

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