Calculus with Applications (10th Edition)

Published by Pearson
ISBN 10: 0321749006
ISBN 13: 978-0-32174-900-0

Chapter 8 - Further Techniques and Applications of Integration - 8.4 Improper Integrals - 8.4 Exercises - Page 452: 18

Answer

Divergent

Work Step by Step

\[\begin{align} & \int_{1}^{\infty }{\ln \left| x \right|}dx \\ & \text{From the definition of absolute value} \\ & \int_{1}^{\infty }{\ln \left| x \right|}dx=\int_{1}^{\infty }{\ln x}dx \\ & \text{Then,} \\ & \int_{1}^{\infty }{\ln x}dx=\underset{b\to \infty }{\mathop{\lim }}\,\int_{1}^{b}{\ln x}dx \\ & \text{Integrating} \\ & \text{=}\underset{b\to \infty }{\mathop{\lim }}\,\left[ x\ln x-x \right]_{1}^{b} \\ & \text{=}\underset{b\to \infty }{\mathop{\lim }}\,\left[ \left( b\ln b-b \right)-\left( 1\ln \left( 1 \right)-1 \right) \right] \\ & \text{=}\underset{b\to \infty }{\mathop{\lim }}\,\left[ \left( b\ln b-b \right)+1 \right] \\ & \text{=}\underset{b\to \infty }{\mathop{\lim }}\,\left[ b\left( \ln b-1 \right)+1 \right] \\ & \text{Evaluate when }b\to \infty \\ & \text{=}\infty \cdot \infty+1 \\ & =\infty \\ & \text{ The improper integral diverges} \\ & \text{Divergent} \\ \end{align}\]
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.