Calculus: Early Transcendentals 9th Edition

Published by Cengage Learning
ISBN 10: 1337613924
ISBN 13: 978-1-33761-392-7

Chapter 7 - Section 7.4 - Integration of Rational Functions by Partial Fractions. - 7.4 Exercises - Page 515: 48

Answer

$\frac{5}{4}\ln \left| {{x^{4/5}} - 1} \right| + C$

Work Step by Step

$$\eqalign{ & \int {\frac{1}{{x - {x^{1/5}}}}} dx \cr & {\text{Substitute }}x = {u^5},{\text{ then }}dx = 5{u^4}du \cr & \int {\frac{1}{{x - {x^{1/5}}}}} dx = \int {\frac{1}{{{u^5} - {{\left( {{u^5}} \right)}^{1/5}}}}\left( {5{u^4}} \right)} du \cr & = \int {\frac{{5{u^4}}}{{{u^5} - u}}} du \cr & = \int {\frac{{5{u^3}}}{{{u^4} - 1}}} du \cr & {\text{Rewrite the integrand}} \cr & = \frac{5}{4}\int {\frac{{4{u^3}}}{{{u^4} - 1}}} du \cr & {\text{Integrating}} \cr & = \frac{5}{4}\ln \left| {{u^4} - 1} \right| + C \cr & {\text{Write in terms of }}x,{\text{ }}x = {u^5} \to u = \root 5 \of x \cr & = \frac{5}{4}\ln \left| {{{\left( {\root 5 \of x } \right)}^4} - 1} \right| + C \cr & = \frac{5}{4}\ln \left| {{x^{4/5}} - 1} \right| + C \cr} $$
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