Chapter 2: Problem 20
Determine whether the sequence is convergent or divergent. If it is convergent, find the limit. \(a_{n}=\frac{\pi^{n}}{3^{n}}\)
Short Answer
Expert verified
The sequence is divergent since \( \left(\frac{\pi}{3}\right) > 1 \).
Step by step solution
01
Understand the Sequence Type
The sequence in question is given by \( a_n = \frac{\pi^n}{3^n} \). This is a form of exponential sequence where the base is composed of two parts: \( \pi^n \) and \( 3^n \).
02
Simplify the Sequence
Simplify the sequence by rewriting it as a fraction of two exponential terms with the same exponent: \( a_n = \left(\frac{\pi}{3}\right)^n \). By doing this, we can more readily analyze the behavior as \( n \) approaches infinity.
03
Determine Base of Exponent
In the simplified form, the sequence base is \( \frac{\pi}{3} \). Calculate the value of \( \frac{\pi}{3} \) which is approximately 1.047. Since this value is greater than 1, the sequence will grow as \( n \) increases.
04
Determine Convergence or Divergence
For sequences of the form \( a_n = r^n \), where \(|r| > 1\), the sequence is divergent because it grows without bound. Since \( \frac{\pi}{3} > 1\), \( \left(\frac{\pi}{3}\right)^n \) diverges.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Exponential Sequences
Exponential sequences are a fundamental concept in understanding arithmetic progressions that involve exponential growth or decay. In such sequences, each term is generated by raising a base number to the power of the term index, usually denoted by \( n \). For instance, the sequence \( a_n = \frac{\pi^n}{3^n} \) can be viewed as exponentially progressing because each element involves an exponentiation process with a constant ratio between consecutive terms. Exponential sequences of the form \( r^n \) exhibit different behaviors depending on the value of the base \( r \).
- If \( |r| > 1 \), the sequence exhibits exponential growth and becomes very large as \( n \) increases, thus the sequence is considered divergent.
- If \( |r| < 1 \), the terms of the sequence approach zero as \( n \) increases, leading to a convergent sequence.
- If \( |r| = 1 \), the behavior typically needs further scrutiny outside basic exponential analysis.
Limits of Sequences
The concept of limits of sequences is a cornerstone in mathematical analysis that helps to determine whether a sequence converges or diverges. When analyzing the limit of a sequence, we observe if the terms approach a specific value as the sequence progresses towards infinity.For the sequence in question, \( a_n = \left(\frac{\pi}{3}\right)^n \), it can only converge if the sequence approaches a finite limit. The limit behavior heavily relies on the base of the exponential part. Calculating \( \frac{\pi}{3} \) yields approximately 1.047, a value greater than one, indicating that the terms of the sequence grow without bound.Consistently, mathematically, if \( |r| \geq 1 \), a sequence \( r^n \) with a large enough \( n \) will either diverge to infinity or not settle to finite value. Here, as \( n \) increases, the sequence grows indefinitely, pointing out that the limit as \( n \) approaches infinity is not finite, thus the sequence is divergent.
Sequence Convergence Analysis
Analyzing the convergence or divergence of sequences involves checking the long-term behavior of the sequence terms. It mainly focuses on recognizing a pattern that indicates if the terms settle to a particular value or grow without limits.For the sequence \( a_n = \left(\frac{\pi}{3}\right)^n \), convergence analysis starts by identifying the formula format, in this case, \( r^n \) where \( r = \frac{\pi}{3} \). The core analysis relies on determining if the limit exists as \( n \) approaches infinity.
- For bases \( |r| \gt 1 \), the sequence diverges since terms expand outward infinitely, which is the case here with \( r = 1.047 \).
- For bases \( |r| < 1 \), terms decrease toward zero, indicating convergence.