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 - 7.6 Using Computer Algebra Systems And Tables Of Integrals - Exercises Set 7.6 - Page 532: 51

Answer

$$ = - \sqrt {5 + 4x - {x^2}} + 2{\sin ^{ - 1}}\left( {\frac{{x - 2}}{3}} \right) + C $$

Work Step by Step

$$\eqalign{ & \int {\frac{x}{{\sqrt {5 + 4x - {x^2}} }}} dx \cr & {\text{completing the square for the radicand}} \cr & = - \left( {{x^2} - 4x - 5} \right) \cr & = - \left( {{x^2} - 4x + 4 - 4 - 5} \right) \cr & = - \left[ {{{\left( {x - 2} \right)}^2} - 9} \right] \cr & = 9 - {\left( {x - 2} \right)^2} \cr & \cr & \int {\frac{x}{{\sqrt {5 + 4x - {x^2}} }}} dx = \int {\frac{x}{{\sqrt {9 - {{\left( {x - 2} \right)}^2}} }}} dx \cr & {\text{make }}u = x - 2,\,\,\,\,{\text{then}}\,\,\,\,\,\,du = dx \cr & \int {\frac{x}{{\sqrt {9 - {{\left( {x - 2} \right)}^2}} }}} dx = \int {\frac{{u + 2}}{{\sqrt {9 - {u^2}} }}} du \cr & = \int {\frac{u}{{\sqrt {9 - {u^2}} }}} du + \int {\frac{2}{{\sqrt {9 - {u^2}} }}} du \cr & = - \frac{1}{2}\int {\frac{{ - 2u}}{{\sqrt {9 - {u^2}} }}} du + \int {\frac{2}{{\sqrt {9 - {u^2}} }}} du \cr & = - \sqrt {9 - {u^2}} + \int {\frac{2}{{\sqrt {9 - {u^2}} }}} du \cr & \cr & {\text{Use the Endpaper Integral Table to evaluate the integral }}\int {\frac{2}{{\sqrt {9 - {u^2}} }}} du \cr & {\text{By formula 77}} \cr & \left( {77} \right):\,\,\,\,\,\,\int {\frac{{du}}{{\sqrt {{a^2} - {u^2}} }}} = {\sin ^{ - 1}}\left( {\frac{u}{a}} \right) + C \cr & \int {\frac{2}{{\sqrt {9 - {u^2}} }}} du = 2{\sin ^{ - 1}}\left( {\frac{u}{3}} \right) + C \cr & \cr & {\text{write in terms of }}x{\text{; replace }}x - 2{\text{ for }}u \cr & = 2{\sin ^{ - 1}}\left( {\frac{{x - 2}}{3}} \right) + C \cr & {\text{then}} \cr & - \sqrt {9 - {u^2}} + \int {\frac{2}{{\sqrt {9 - {u^2}} }}} du = - \sqrt {9 - {{\left( {x - 2} \right)}^2}} + 2{\sin ^{ - 1}}\left( {\frac{{x - 2}}{3}} \right) + C \cr & = - \sqrt {5 + 4x - {x^2}} + 2{\sin ^{ - 1}}\left( {\frac{{x - 2}}{3}} \right) + C \cr} $$
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