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: 28

Answer

$-\frac{135}{64(3x+2)}+\frac{109}{64(x-2)}+\frac{9}{8(x-2)^2}$

Work Step by Step

Step 1. Factor the denominator as $(3x+2)(x-2)^2$ Step 2. Assume the end results as $\frac{A}{3x+2}+\frac{B}{x-2}+\frac{C}{(x-2)^2}$ Step 3. Combine the above functions as: $\frac{A(x-2)^2+B(3x+2)(x-2)+C(3x+2)}{(3x+2)(x-2)^2}=\frac{(A+3B)x^2+(-4A-4B+3C)x+(4A-4B+2C)}{(3x+2)(x-2)^2}$ Step 4. Compare the above result with the original to set up the following system of equations: \begin{cases} A+3B=3 \\ -4A-4B+3C=5 \\ 4A-4B+2C=-13 \end{cases} Step 5. Add the last two equations to get $-8B+5C=-8$ which gives $C=\frac{8B-8}{5}$ Step 6 Use $A=3-3B$ together with the above result to back substitute into the last equation and solve for $B$ to get $B=\frac{109}{64}$ Step 7. Get the other parameters as $A=\frac{-135}{64}$ and $C=\frac{9}{8}$ Step 8. Write the end results as: $-\frac{135}{64(3x+2)}+\frac{109}{64(x-2)}+\frac{9}{8(x-2)^2}$
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