Calculus 8th Edition

Published by Cengage
ISBN 10: 1285740629
ISBN 13: 978-1-28574-062-1

Chapter 7 - Techniques of Integration - 7.4 Integration of Rational Functions by Partial Fractions - 7.4 Exercises - Page 541: 30

Answer

$\frac{1}{2}\left(\frac{1}{2}\ln|x^2+3|-\frac{1}{\sqrt 3}\tan^{-1}\left(\frac{x}{\sqrt 3}\right)+\frac{1}{2}\ln|x^2+1|-3\tan^{-1}x\right)+C$

Work Step by Step

$\int\frac{x^{3}-2x^{2}+2x-5}{x^{4}+4x^{2}+3}dx$ = $\int\left[\frac{x^{3}-2x^{2}+2x-5}{(x^{2}+3)(x^{2}+1)}\right]dx$ = $\int\left(\frac{Ax+B}{x^{2}+3}+\frac{Cx+D}{x^{2}+1}\right)dx$ $x^{3}-2x^{2}+2x-5$ = $(Ax+B)(x^{2}+1)+(Cx+D)(x^{2}+3)$ $x^{3}-2x^{2}+2x-5$ = $(Ax^3+Bx^2+Ax+B)+(Cx^3+Dx^2+3Cx+3D)$ $1$ = $A+C$ $-2$ = $B+D$ $2$ = $A+3C$ $-5$ = $B+3D$ $A$ = $\frac{1}{2}$, $B$ = $-\frac{1}{2}$, $C$ = $\frac{1}{2}$, $D$ = $-\frac{3}{2}$ So $\int\frac{x^{3}-2x^{2}+2x-5}{x^{4}+4x^{2}+3}dx$ = $\int{\frac{1}{2}}\left(\frac{x-1}{x^{2}+3}+\frac{x-3}{x^{2}+1}\right)dx$ = $\int{\frac{1}{2}}\left[\frac{x}{x^{2}+3}-\frac{1}{x^{2}+3}+\frac{x}{x^{2}+1}-\frac{3}{x^{2}+1}\right]dx$ = $\frac{1}{2}\left[\frac{1}{2}\ln|x^2+3|-\frac{1}{\sqrt 3}\tan^{-1}\left(\frac{x}{\sqrt 3}\right)+\frac{1}{2}\ln|x^2+1|-3\tan^{-1}x\right]+C$
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