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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 10.8.83

11–86. Applying convergence tests Determine whether the following series converge. Justify your answers.
∑ (from j = 2 to ∞)1 / (j ln¹⁰j)

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Identify the series given: \( \sum_{j=2}^{\infty} \frac{1}{j (\ln j)^{10}} \). This is a positive term series, so we can consider convergence tests suitable for positive series.
Recognize that the series resembles a p-series with an additional logarithmic factor in the denominator. Since \( j \) grows linearly and \( (\ln j)^{10} \) grows slower than any power of \( j \), we should consider the Integral Test for convergence.
Set up the Integral Test by considering the integral \( \int_{2}^{\infty} \frac{1}{x (\ln x)^{10}} \, dx \). If this improper integral converges, then the series converges; if it diverges, the series diverges.
Make the substitution \( u = \ln x \), which implies \( du = \frac{1}{x} dx \). This transforms the integral into \( \int_{\ln 2}^{\infty} \frac{1}{u^{10}} \, du \).
Evaluate the integral \( \int_{\ln 2}^{\infty} u^{-10} \, du \). Since this is an integral of a power function \( u^{-p} \) with \( p = 10 > 1 \), it converges. Therefore, by the Integral Test, the original series converges.

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