Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 10 - Section 10.7 - Partial Fractions - 10.7 Exercises - Page 751: 48

Answer

Yes, see explanations.

Work Step by Step

Step 1. Find a common denominator and add up the rational polynomials to get: $\frac{2(x-1)(x+1)+(x+1)+(x-1)^2}{(x+1)(x-1)^2}=\frac{3x^2-x}{(x+1)(x-1)^2}$ Step 2. To decompose the above rational polynomial, assume it will take the form: $\frac{A}{x+1}+\frac{B}{x-1}+\frac{C}{(x-1)^2}$ Step 3. Use a common denominator, add up the terms above to get: $\frac{A(x-1)^2+B(x+1)(x-1)+C(x+1)}{(x+1)(x-1)^2}=\frac{(A+B)x^2+(-2A+C)x+(A-B+C)}{(x+1)(x-1)^2}$ Step 4. Compare the above results with the expression of setp-1 to set up the following equations: \begin{cases} A+B=3 \\ -2A+C=-1\\A-B+C=0 \end{cases} Step 5. Use $B=3-A, C=2A-1$ for substitution, we get $A=1, B=2, C=1$ Step 6. The decomposed form in step-2 becomes: $\frac{1}{x+1}+\frac{2}{x-1}+\frac{1}{(x-1)^2}$ which is the same as the original expression given in the Exercise.
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