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Ch. 8 - Integration Techniques
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243Non è quello che usi tu?Cambia libro di testo
Capitolo 8, Problema 8.9.10

7–58. Improper integrals Evaluate the following integrals or state that they diverge.
10. ∫ (from 0 to ∞) e⁻²ˣ dx

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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 \(\int_0^{\infty} e^{-2x} \, dx\).
Rewrite the integral as a limit to handle the infinite upper bound: Express the integral as \(\lim_{t \to \infty} \int_0^t e^{-2x} \, dx\).
Find the antiderivative of the integrand \(e^{-2x}\): Recall that the integral of \(e^{ax}\) with respect to \(x\) is \(\frac{1}{a} e^{ax}\), so here the antiderivative is \(-\frac{1}{2} e^{-2x}\).
Evaluate the definite integral from 0 to \(t\) using the antiderivative: Substitute the limits to get \(\left[-\frac{1}{2} e^{-2x} \right]_0^t = -\frac{1}{2} e^{-2t} + \frac{1}{2}\).
Take the limit as \(t\) approaches infinity: Calculate \(\lim_{t \to \infty} \left(-\frac{1}{2} e^{-2t} + \frac{1}{2}\right)\) to determine if the integral converges or diverges.

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