Calculus, 10th Edition (Anton)

Published by Wiley
ISBN 10: 0-47064-772-8
ISBN 13: 978-0-47064-772-1

Chapter 7 - Principles Of Integral Evaluation - 7.8 Improper Integrals - Exercises Set 7.8 - Page 554: 17

Answer

$${\text{diverges}}$$

Work Step by Step

$$\eqalign{ & \int_0^4 {\frac{{dx}}{{{{\left( {x - 4} \right)}^2}}}} \cr & {\text{The function is undefined for }}x = 4,{\text{ so the integral can be represented as}} \cr & \int_0^4 {\frac{{dx}}{{{{\left( {x - 4} \right)}^2}}}} = \mathop {\lim }\limits_{k \to {4^ - }} \int_0^k {\frac{{dx}}{{{{\left( {x - 4} \right)}^2}}}} \cr & {\text{Integrate}} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \mathop {\lim }\limits_{k \to {4^ - }} \left[ { - \frac{1}{{x - 4}}} \right]_0^k \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \mathop {\lim }\limits_{k \to {4^ - }} \left[ { - \frac{1}{{k - 4}} + \frac{1}{{0 - 4}}} \right] \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \mathop {\lim }\limits_{k \to {4^ - }} \left[ { - \frac{1}{{k - 4}} - \frac{1}{4}} \right] \cr & \,{\text{Calculate the limit when }}k \to {4^ - } \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = - \frac{1}{{{0^ - }}} - \frac{1}{4} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = + \infty \cr & {\text{Then}}{\text{,}} \cr & \int_0^4 {\frac{{dx}}{{{{\left( {x - 4} \right)}^2}}}} = + \infty \cr & {\text{The integral diverges}} \cr} $$
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