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Ch. 8 - Integration Techniques
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243당신이 사용하는 게 아니라요?교과서 변경
8장, 문제 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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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Improper Integrals

Improper integrals involve integration over an infinite interval or integrands with infinite discontinuities. To evaluate them, limits are used to handle the infinite bounds or singularities, determining if the integral converges to a finite value or diverges.
추천 영상:
11:11
Improper Integrals: Infinite Intervals

Exponential Decay Functions

Exponential decay functions, like e^(-2x), decrease rapidly as x increases. Their integrals over infinite intervals often converge because the function approaches zero fast enough, making the area under the curve finite.
추천 영상:
09:29
Exponential Growth & Decay

Evaluating Definite Integrals Using Limits

When integrating over infinite limits, the definite integral is expressed as a limit of integrals with finite bounds. This approach allows calculation of the integral's value by taking the limit as the bound approaches infinity.
추천 영상:
05:43
Definition of the Definite Integral