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Ch. 10 - Sequences and Infinite Series
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243Non è quello che usi tu?Cambia libro di testo
Capitolo 10, Problema 10.2.5

For what values of r does the sequence {rⁿ} converge? Diverge?

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Recall that the sequence is given by \(a_n = r^n\), where \(n\) is a natural number and \(r\) is a real number parameter.
To determine convergence or divergence, analyze the behavior of \(r^n\) as \(n\) approaches infinity for different values of \(r\).
Consider the cases based on the absolute value of \(r\): - If \(|r| < 1\), then \(r^n\) approaches 0 as \(n \to \infty\), so the sequence converges to 0. - If \(|r| = 1\), then: * If \(r = 1\), the sequence is constant and converges to 1. * If \(r = -1\), the sequence oscillates between 1 and -1 and does not converge. - If \(|r| > 1\), then \(r^n\) grows without bound in magnitude, so the sequence diverges.
Summarize the results: - Converges to 0 if \(|r| < 1\). - Converges to 1 if \(r = 1\). - Diverges if \(|r| > 1\) or if \(r = -1\) (due to oscillation).
Therefore, the key step is to analyze the absolute value of \(r\) and apply the limit definition of convergence for sequences.

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