Calculus with Applications (10th Edition)

Published by Pearson
ISBN 10: 0321749006
ISBN 13: 978-0-32174-900-0

Chapter 8 - Further Techniques and Applications of Integration - Chapter Review - Review Exercises - Page 455: 24

Answer

$A = \frac{7}{4}\left( {{e^2} - 1} \right)$

Work Step by Step

$$\eqalign{ & y = \left( {3 + {x^2}} \right){e^{2x}},{\text{ from }}x = 0{\text{ to }}x = 1 \cr & {\text{The area is given by}} \cr & A = \int_0^1 {\left( {3 + {x^2}} \right){e^{2x}}} dx \cr & {\text{Integrate by parts}} \cr & u = 3 + {x^2},{\text{ }}du = 2xdx \cr & du = {e^{2x}},{\text{ }}v = \frac{1}{2}{e^{2x}} \cr & \int {\left( {3 + {x^2}} \right){e^{2x}}} dx = \frac{1}{2}\left( {3 + {x^2}} \right){e^{2x}} - \int {x{e^{2x}}dx} \cr & {\text{Integrate by parts }}\int {x{e^{2x}}dx} \cr & u = x,{\text{ }}du = dx \cr & du = {e^{2x}},{\text{ }}v = \frac{1}{2}{e^{2x}} \cr & \int {\left( {3 + {x^2}} \right){e^{2x}}} dx = \frac{1}{2}\left( {3 + {x^2}} \right){e^{2x}} - \underbrace {\int {x{e^{2x}}dx} }_ \downarrow \cr & \int {\left( {3 + {x^2}} \right){e^{2x}}} dx = \frac{1}{2}\left( {3 + {x^2}} \right){e^{2x}} - \left( {\frac{1}{2}x{e^{2x}} - \int {\frac{1}{2}{e^{2x}}} dx} \right) \cr & \int {\left( {3 + {x^2}} \right){e^{2x}}} dx = \frac{1}{2}\left( {3 + {x^2}} \right){e^{2x}} - \frac{1}{2}x{e^{2x}} + \frac{1}{2}\int {{e^{2x}}} dx \cr & \int {\left( {3 + {x^2}} \right){e^{2x}}} dx = \frac{1}{2}\left( {3 + {x^2}} \right){e^{2x}} - \frac{1}{2}x{e^{2x}} + \frac{1}{4}{e^{2x}} \cr & {\text{Therefore}}{\text{,}} \cr & A = \int_0^1 {\left( {3 + {x^2}} \right){e^{2x}}} dx \cr & A = \left[ {\frac{1}{2}\left( {3 + {x^2}} \right){e^{2x}} - \frac{1}{2}x{e^{2x}} + \frac{1}{4}{e^{2x}}} \right]_0^1 \cr & A = \left[ {\frac{1}{2}\left( {3 + {{\left( 1 \right)}^2}} \right){e^2} - \frac{1}{2}{e^2} + \frac{1}{4}{e^2}} \right] - \left[ {\frac{1}{2}\left( 3 \right){e^0} - 0 + \frac{1}{4}} \right] \cr & A = \frac{7}{4}{e^2} - \frac{7}{4} \cr & A = \frac{7}{4}\left( {{e^2} - 1} \right) \cr & A \approx 11.18 \cr} $$
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