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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 10.1.47

45–48. {Use of Tech} Explicit formulas for sequences Consider the formulas for the following sequences {aₙ}ₙ₌₁∞
 Make a table with at least ten terms and determine a plausible limit of the sequence or state that the sequence diverges.
aₙ = ⁿ² + n ;n = 1, 2, 3, …

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1
Identify the given sequence formula: \(a_n = n^2 + n\) for \(n = 1, 2, 3, \ldots\).
Create a table of values by substituting \(n\) from 1 to 10 into the formula to find the first ten terms: calculate \(a_1, a_2, \ldots, a_{10}\).
Observe the pattern of the terms in the table to see how the sequence behaves as \(n\) increases.
Analyze the growth of the terms by considering the dominant term \(n^2\) in the formula, which suggests how the sequence behaves for large \(n\).
Based on the behavior of the terms, determine whether the sequence approaches a finite limit or diverges to infinity.

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Key Concepts

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

Sequences and Their Terms

A sequence is an ordered list of numbers defined by a specific formula for its terms. Each term aₙ depends on the index n, which usually starts at 1 and increases by 1. Understanding how to generate terms from the explicit formula is essential for analyzing the sequence's behavior.
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Limits of Sequences

The limit of a sequence describes the value that the terms approach as n becomes very large. If the terms get arbitrarily close to a finite number, the sequence converges; otherwise, it diverges. Determining the limit helps understand the long-term behavior of the sequence.
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Using Tables and Numerical Approximations

Creating a table of terms allows visualization of the sequence's progression and helps identify patterns or trends. By calculating several terms, one can estimate whether the sequence approaches a finite limit or grows without bound, aiding in conjecturing convergence or divergence.
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Finding Limits Numerically and Graphically