Chapter 9: Problem 25
Find a formula for the \(n\) th term of the sequence. \(1,0,1,0,1, \ldots\) Alternating \(1^{\prime}\) s and \(0^{\prime}\) s
Short Answer
Expert verified
The formula is \(a_n = \frac{1 + (-1)^{n-1}}{2}\).
Step by step solution
01
Analyze the sequence pattern
Observe the given sequence: \(1, 0, 1, 0, 1, \ldots\). It's clear that the sequence alternates between 1 and 0. This indicates a repeating pattern: every odd position in the sequence has a 1, and every even position has a 0.
02
Identify the positions of terms
Notice that when the term is in the first position \((n=1)\), third position \((n=3)\), fifth position \((n=5)\) and so on, it has a value of 1. Conversely, for even positions \((n=2, 4, 6, \ldots)\), the term has a value of 0.
03
Develop the formula based on odd/even positions
For this alternating pattern, we can use the properties of the even and odd numbers. Use the condition that powers of \((-1)\), where \((-1)^n\), produce a 1 for even \(n\) and -1 for odd \(n\). The expression \((1 + (-1)^n)/2\) gives 1 for odd \(n\) and 0 for even \(n\).
04
Write the formula for the nth term
The formula for the nth term of the sequence is given by:\[a_n = \frac{1 + (-1)^{n-1}}{2}\]This formula will yield 1 when \(n\) is odd and 0 when \(n\) is even, matching the sequence's pattern.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Alternating Sequence
An alternating sequence is a sequence of numbers in which the terms alternate in a specific pattern. In the case of our sequence, the pattern alternates between 1 and 0. This means that the sequence follows a predictable order, switching from one number to the next and then back again in a repeating cycle.
Understanding alternating sequences is crucial because they can help us identify the formula for the sequence. Recognizing that our sequence goes: 1, 0, 1, 0, and so on, tells us that it has a solid structure that we can harness to formulate a pattern.
Understanding alternating sequences is crucial because they can help us identify the formula for the sequence. Recognizing that our sequence goes: 1, 0, 1, 0, and so on, tells us that it has a solid structure that we can harness to formulate a pattern.
- The sequence alternates in fixed positions, with 1s in odd positions and 0s in even positions.
- This type of sequence is common in mathematical problems that involve periodic or cyclical changes.
Odd and Even Positions
In analyzing sequences, odd and even positions play a vital role in distinguishing the pattern. Odd positions are simply the positions in a sequence represented by odd numbers: 1st, 3rd, 5th, and so on. Even positions are represented by even numbers: 2nd, 4th, 6th, etc.
For the sequence in question, the relationship is straightforward: odd positions contain the number 1, while even positions contain the number 0. This type of separation simplifies the identification of a formula because the differences between consecutive numbers (0s followed by 1s) directly correlate to their positions.
For the sequence in question, the relationship is straightforward: odd positions contain the number 1, while even positions contain the number 0. This type of separation simplifies the identification of a formula because the differences between consecutive numbers (0s followed by 1s) directly correlate to their positions.
- Odd positions \(1, 3, 5, \ldots\) yield a 1.
- Even positions \(2, 4, 6, \ldots\) yield a 0.
Sequence Pattern Analysis
Analyzing a sequence pattern involves closely examining the order and repetition in a sequence of numbers. For this exercise, the sequence follows a straightforward pattern of alternating numbers between 1 and 0. Conducting a sequence pattern analysis allows us to derive a consistent rule or formula for any term based on its position number.
A logical step in sequence pattern analysis for this sequence was to observe that odd positions (1, 3, 5, etc.) always contained a 1, while even positions (2, 4, 6, etc.) always contained a 0.
A logical step in sequence pattern analysis for this sequence was to observe that odd positions (1, 3, 5, etc.) always contained a 1, while even positions (2, 4, 6, etc.) always contained a 0.
- The general approach in this situation is to utilize mathematical operations that align with the discovered pattern.
- For example, employing powers of (-1) such that \((-1)^{n-1}\) yields -1 in odd positions and 1 in even ones.