Thomas' Calculus 13th Edition

Published by Pearson
ISBN 10: 0-32187-896-5
ISBN 13: 978-0-32187-896-0

Chapter 8: Techniques of Integration - Section 8.2 - Integration by Parts - Exercises 8.2 - Page 455: 43

Answer

$$\frac{2}{9}{x^{3/2}}\left( {3\ln x - 2} \right) + C $$

Work Step by Step

$$\eqalign{ & \int {\sqrt x \ln x} dx \cr & = \int {{x^{1/2}}\ln x} dx \cr & {\text{Using integration by parts method }} \cr & \,\,\,\,\,{\text{Let }}u = \ln x,\,\,\,\,du = \frac{1}{x}dx,\,\,\,\,dv = {x^{1/2}}dt,\,\,\,\,v = \frac{2}{3}{x^{3/2}} \cr & {\text{Integration by parts then gives}} \cr & \int {{x^{1/2}}\ln x} dx = \frac{2}{3}{x^{3/2}}\ln x - \int {\left( {\frac{2}{3}{x^{3/2}}} \right)\left( {\frac{1}{x}dx} \right)} \cr & \int {{x^{1/2}}\ln x} dx = \frac{2}{3}{x^{3/2}}\ln x - \frac{2}{3}\int {{x^{1/2}}} dx \cr & \int {{x^{1/2}}\ln x} dx = \frac{2}{3}{x^{3/2}}\ln x - \frac{2}{3}\left( {\frac{{{x^{3/2}}}}{{3/2}}} \right) + C \cr & {\text{simplifying}} \cr & \int {{x^{1/2}}\ln x} dx = \frac{2}{3}{x^{3/2}}\ln x - \frac{4}{9}{x^{3/2}} + C \cr & \int {{x^{1/2}}\ln x} dx = \frac{2}{9}{x^{3/2}}\left( {3\ln x - 2} \right) + C \cr} $$
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