Calculus: Early Transcendentals (2nd Edition)

Published by Pearson
ISBN 10: 0321947347
ISBN 13: 978-0-32194-734-5

Chapter 13 - Multiple Integration - 13.1 Double Integrals over Rectangular Regions - 13.1 Exercises - Page 971: 23

Answer

$$\frac{{9 - {e^2}}}{2}$$

Work Step by Step

$$\eqalign{ & \iint\limits_R {{e^{x + 2y}}}dA;\,\,\,\,\,\,\,R = \left\{ {\left( {x,y} \right):0 \leqslant x \leqslant \ln 2,\,\,\,\,1 \leqslant y \leqslant \ln 3} \right\} \cr & {\text{Convert to an iterated integral substituting the region }}R \cr & = \int_1^{\ln 3} {\int_0^{\ln 2} {{e^{x + 2y}}} } dxdy \cr & = \int_1^{\ln 3} {\left[ {\int_0^{\ln 2} {{e^{x + 2y}}} dx} \right]} dy \cr & {\text{solve the inner integral}}{\text{, treat }}y{\text{ as a constant}} \cr & = \int_0^{\ln 2} {{e^{x + 2y}}} dx \cr & {\text{integrating}} \cr & = \left( {{e^{x + 2y}}} \right)_0^{\ln 2} \cr & {\text{evaluating the limits for the variable }}x \cr & = {e^{\ln 2 + 2y}} - {e^{0 + 2y}} \cr & {\text{simplifying}} \cr & = {e^{\ln 2 + 2y}} - {e^{2y}} \cr & \cr & \int_1^{\ln 3} {\left[ {\int_0^{\ln 2} {{e^{x + 2y}}} dx} \right]} dy = \int_1^{\ln 3} {\left( {{e^{\ln 2 + 2y}} - {e^{2y}}} \right)} dy \cr & {\text{integrating}} \cr & = \left( {\frac{1}{2}{e^{\ln 2 + 2y}} - \frac{1}{2}{e^{2y}}} \right)_1^{\ln 3} \cr & {\text{evaluate}} \cr & = \frac{1}{2}\left( {{e^{\ln 2 + 2\ln 3}} - {e^{2\ln 3}}} \right) - \frac{1}{2}\left( {{e^{\ln 2 + 2\left( 1 \right)}} - {e^{2\left( 1 \right)}}} \right) \cr & = \frac{1}{2}\left( {18 - 9} \right) - \frac{1}{2}\left( {2{e^2} - {e^2}} \right) \cr & = \frac{9}{2} - \frac{1}{2}{e^2} \cr & = \frac{{9 - {e^2}}}{2} \cr} $$
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