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 - 7.5 Integrating Rational Functions By Partial Fractions - Exercises Set 7.5 - Page 521: 24

Answer

$$\frac{1}{x} + 3\ln \left| {x - 1} \right| + C$$

Work Step by Step

$$\eqalign{ & \int {\frac{{3{x^2} - x + 1}}{{{x^3} - {x^2}}}} dx \cr & = \int {\frac{{3{x^2} - x + 1}}{{{x^2}\left( {x - 1} \right)}}} dx \cr & {\text{Decompose the integrand into partial fractions}} \cr & \frac{{3{x^2} - x + 1}}{{{x^2}\left( {x - 1} \right)}} = \frac{A}{x} + \frac{B}{{{x^2}}} + \frac{C}{{x - 1}} \cr & 3{x^2} - x + 1 = A\left( x \right)\left( {x - 1} \right) + B\left( {x - 1} \right) + C{x^2} \cr & 3{x^2} - x + 1 = A{x^2} - Ax + Bx - B + C{x^2} \cr & {\text{Collect like terms}} \cr & 3{x^2} - x + 1 = \left( {A{x^2} + C{x^2}} \right) + \left( { - Ax + Bx} \right) - B \cr & A + C = 3,{\text{ }} - A + B = - 1,{\text{ }}B = - 1 \cr & {\text{Solving we obtain}} \cr & A = 0,{\text{ }}B = - 1,{\text{ }}C = 3 \cr & {\text{Then}} \cr & \frac{{3{x^2} - x + 1}}{{{x^2}\left( {x - 1} \right)}} = - \frac{1}{{{x^2}}} + \frac{3}{{x - 1}} \cr & \int {\frac{{3{x^2} - x + 1}}{{{x^3} - {x^2}}}} dx = - \int {\frac{1}{{{x^2}}}} dx + \int {\frac{3}{{x - 1}}dx} \cr & {\text{ }} = \frac{1}{x} + 3\ln \left| {x - 1} \right| + C \cr} $$
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