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Ch. 8 - Techniques of Integration
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Non è quello che usi tu?Cambia libro di testo
Capitolo 8, Problema 8.PE.63

Which of the improper integrals in Exercises 63–68 converge and which diverge?
∫ from 6 to ∞ of (1 / √(θ² + 1)) dθ

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1
Identify the type of improper integral: Since the upper limit of integration is infinity, this is an improper integral of the form \(\int_{6}^{\infty} \frac{1}{\sqrt{\theta^{2} + 1}} \, d\theta\).
Set up the integral as a limit: Rewrite the integral as \(\lim_{t \to \infty} \int_{6}^{t} \frac{1}{\sqrt{\theta^{2} + 1}} \, d\theta\) to handle the infinite upper bound.
Find the antiderivative: Recognize that the integral of \(\frac{1}{\sqrt{\theta^{2} + 1}}\) with respect to \(\theta\) is \(\sinh^{-1}(\theta)\) or equivalently \(\ln\left(\theta + \sqrt{\theta^{2} + 1}\right)\).
Evaluate the definite integral from 6 to \(t\): Substitute the limits into the antiderivative to get \(\sinh^{-1}(t) - \sinh^{-1}(6)\) or \(\ln\left(t + \sqrt{t^{2} + 1}\right) - \ln\left(6 + \sqrt{36 + 1}\right)\).
Take the limit as \(t\) approaches infinity: Analyze \(\lim_{t \to \infty} \sinh^{-1}(t)\) or \(\lim_{t \to \infty} \ln\left(t + \sqrt{t^{2} + 1}\right)\) to determine if the integral converges (finite limit) or diverges (infinite limit).

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