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Ch. 8 - Techniques of Integration
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Not the one you use?Change textbook
Chapter 8, Problem 8.8.2

The integrals in Exercises 1–34 converge. Evaluate the integrals without using tables.
∫₁^∞ dx / x^1.001

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1
Identify the integral as an improper integral because the upper limit is infinity: \(\int_1^{\infty} \frac{dx}{x^{1.001}}\).
Rewrite the integral using exponent notation: \(\int_1^{\infty} x^{-1.001} \, dx\).
Find the antiderivative of the integrand. Recall that for \(\int x^n \, dx = \frac{x^{n+1}}{n+1} + C\) when \(n \neq -1\). Here, \(n = -1.001\), so the antiderivative is \(\frac{x^{-0.001}}{-0.001} + C\).
Set up the limit for the improper integral: \(\lim_{t \to \infty} \left[ \frac{x^{-0.001}}{-0.001} \right]_1^{t}\).
Evaluate the limit by substituting the bounds and simplifying the expression to find the value of the integral.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Improper Integrals

Improper integrals involve integration over an infinite interval or integrands with infinite discontinuities. To evaluate them, we replace the infinite limit with a variable and take the limit as it approaches infinity, ensuring the integral converges to a finite value.
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A p-integral of the form ∫₁^∞ 1/x^p dx converges if and only if p > 1. This condition ensures the area under the curve decreases sufficiently fast to produce a finite result, which is crucial for determining whether the given integral converges.
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