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Ch. 10 - Sequences and Infinite Series
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243Not the one you use?Change textbook
Chapter 10, Problem 10.2.13

13–52. Limits of sequences
Find the limit of the following sequences or determine that the sequence diverges.


{n³⁄(n⁴ + 1)}  

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1
Identify the given sequence: \(a_n = \frac{n^3}{n^4 + 1}\).
To find the limit as \(n\) approaches infinity, analyze the highest powers of \(n\) in the numerator and denominator.
Divide both the numerator and denominator by \(n^4\), the highest power in the denominator, to simplify the expression: \(a_n = \frac{\frac{n^3}{n^4}}{\frac{n^4}{n^4} + \frac{1}{n^4}} = \frac{\frac{1}{n}}{1 + \frac{1}{n^4}}\).
Evaluate the limit of each part as \(n \to \infty\): \(\frac{1}{n} \to 0\) and \(\frac{1}{n^4} \to 0\), so the expression simplifies to \(\frac{0}{1 + 0} = 0\).
Conclude that the limit of the sequence \(a_n\) as \(n\) approaches infinity is 0.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Limits of Sequences

The limit of a sequence describes the value that the terms of the sequence approach as the index n becomes very large. If the terms get arbitrarily close to a specific number, the sequence converges to that limit; otherwise, it diverges.
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Introduction to Sequences

Dominant Term Analysis

When evaluating limits of sequences involving polynomials, focus on the highest degree terms in the numerator and denominator. These dominant terms determine the behavior of the sequence as n approaches infinity, simplifying the limit calculation.
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Behavior of Rational Functions at Infinity

For sequences defined by rational functions, the limit as n approaches infinity depends on the degrees of the numerator and denominator polynomials. If the numerator's degree is less, the limit is zero; if equal, the limit is the ratio of leading coefficients; if greater, the sequence diverges.
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