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 750: 38

Answer

$\frac{3}{x-1}-\frac{2}{x^2+2}$

Work Step by Step

Step 1. Factor the denominator as: $x^3+2x-(x^2+2)=(x^2+2)(x-1)$ Step 2. Assume the end results as: $\frac{A}{x-1}+\frac{Bx+C}{x^2+2}$ Step 3. Combine the above functions as: $\frac{A(x^2+2)+(Bx+C)(x-1)}{(x^2+2)(x-1)}=\frac{(A+B)x^2+(-B+C)x+(2A-C)}{(x^2+2)(x-1)}$ Step 4. Compare the above result with the original expression to set up the following system of equations: \begin{cases} A+B=3 \\ -B+C=-2\\2A-C=8 \end{cases} Step 5. Add up all equations to get $3A=9$ or $A=3$, use substitution to get $B=0, C=-2$ Step 6. Write the final results as: $\frac{3}{x-1}-\frac{2}{x^2+2}$
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