Thomas' Calculus 13th Edition

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

Chapter 7: Transcendental Functions - Section 7.2 - Natural Logarithms - Exercises 7.2 - Page 381: 53

Answer

$$\ln \left| {1 + \sqrt x } \right| + C $$

Work Step by Step

$$\eqalign{ & \int {\frac{{dx}}{{2\sqrt x + 2x}}} \cr & {\text{Factoring }}2\sqrt x + 2x,{\text{ the common factor is 2}}\sqrt x \cr & = \int {\frac{{dx}}{{2\sqrt x \left( {1 + \sqrt x } \right)}}} \cr & {\text{Use substitution:}}\cr & {\text{Let }}u = 1 + \sqrt x,{\text{ so that }}du = \frac{1}{{2\sqrt x }}dx \cr & dx = 2\sqrt x du \cr & {\text{Write the integral in terms of }}u \cr & \int {\frac{{dx}}{{2\sqrt x \left( {1 + \sqrt x } \right)}}} = \int {\frac{{2\sqrt x du}}{{2\sqrt x \left( u \right)}}} \cr & = \int {\frac{1}{u}} du \cr & {\text{Integrate }} \cr & = \ln \left| u \right| + C \cr & {\text{Write in terms of }}x:\cr & {\text{Replace }}1 + \sqrt x \tan t{\text{ for }}u \cr & = \ln \left| {1 + \sqrt x } \right| + C \cr} $$
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