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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 10.8.35

11–86. Applying convergence tests Determine whether the following series converge. Justify your answers.
∑ (from k = 1 to ∞) 2⁹k / kᵏ

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First, write down the general term of the series: \(a_k = \frac{2^{9k}}{k^k}\).
To determine convergence, consider applying the Root Test, which is useful for series with terms raised to the power of \(k\). The Root Test uses the limit \(L = \lim_{k \to \infty} \sqrt[k]{|a_k|}\).
Calculate \(\sqrt[k]{|a_k|} = \sqrt[k]{\frac{2^{9k}}{k^k}} = \frac{2^9}{k}\), since \(\sqrt[k]{2^{9k}} = 2^9\) and \(\sqrt[k]{k^k} = k\).
Evaluate the limit \(L = \lim_{k \to \infty} \frac{2^9}{k}\). As \(k\) approaches infinity, \(\frac{2^9}{k}\) approaches 0.
Since \(L = 0 < 1\), by the Root Test, the series \(\sum_{k=1}^\infty \frac{2^{9k}}{k^k}\) converges absolutely.

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