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 - 7.4 Trigonometric Substitutions - Exercises Set 7.4 - Page 514: 40

Answer

$$\frac{1}{4}{\tan ^{ - 1}}\left( {4x + 2} \right) + C$$

Work Step by Step

$$\eqalign{ & \int {\frac{{dx}}{{16{x^2} + 16x + 5}}} \cr & {\text{Completing the square for }}16{x^2} + 16x + 5 \cr & 16{x^2} + 16x + 5 = \left( {16{x^2} + 16x + 4} \right) + 1 \cr & 16{x^2} + 16x + 5 = {\left( {4x + 2} \right)^2} + 1 \cr & \int {\frac{{dx}}{{16{x^2} + 16x + 5}}} = \int {\frac{{dx}}{{{{\left( {4x + 2} \right)}^2} + 1}}} \cr & \cr & {\text{Write in terms of }}u \cr & {\text{Substitute }}u = 4x + 2,{\text{ }}\,\,\,du = 4dx \cr & \int {\frac{{dx}}{{{{\left( {4x + 2} \right)}^2} + 1}}} = \int {\frac{{\left( {1/4} \right)du}}{{{u^2} + 1}}} \cr & = \frac{1}{4}\int {\frac{{du}}{{{u^2} + 1}}} \cr & {\text{Integrate}} \cr & = \frac{1}{4}{\tan ^{ - 1}}u + C \cr & \cr & {\text{Write in terms of }}x \cr & = \frac{1}{4}{\tan ^{ - 1}}\left( {4x + 2} \right) + C \cr} $$
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