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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 10.2.15

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


{(3n³ − 1)⁄(2n³ + 1)}

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1
Identify the given sequence: \(a_n = \frac{3n^3 - 1}{2n^3 + 1}\).
To find the limit as \(n\) approaches infinity, observe the highest power of \(n\) in the numerator and denominator, which is \(n^3\).
Divide both the numerator and the denominator by \(n^3\) to simplify the expression: \(\frac{\frac{3n^3}{n^3} - \frac{1}{n^3}}{\frac{2n^3}{n^3} + \frac{1}{n^3}} = \frac{3 - \frac{1}{n^3}}{2 + \frac{1}{n^3}}\).
As \(n\) approaches infinity, the terms \(\frac{1}{n^3}\) approach 0, so the expression simplifies to \(\frac{3 - 0}{2 + 0} = \frac{3}{2}\).
Conclude that the limit of the sequence is \(\frac{3}{2}\).

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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 is the value that the terms of the sequence approach as the index n goes to infinity. If the terms get arbitrarily close to a specific number, the sequence converges to that limit; otherwise, it diverges.
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Dominant Term in Polynomial Expressions

When evaluating limits of sequences involving polynomials, the highest degree terms dominate the behavior as n becomes large. Lower degree terms become insignificant, so the limit can often be found by comparing the leading terms.
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Limit Laws and Simplification Techniques

Limit laws allow the separation and simplification of complex expressions. For rational sequences, dividing numerator and denominator by the highest power of n helps simplify the expression and find the limit more easily.
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