Precalculus: Mathematics for Calculus, 7th Edition

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

Chapter 10 - Review - Exercises - Page 771: 86

Answer

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

Work Step by Step

Step 1. Factorize the denominator as: $x(x^2-4)=x(x+2)(x-2)$ Step 2. Assume the partial fraction decomposition is: $\frac{A}{x}+\frac{B}{x+2}+\frac{C}{x-2}$ Step 3. Combine the rational functions above: $\frac{A(x^2-4)+Bx(x-2)+Cx(x+2)}{x(x+2)(x-2)}=\frac{(A+B+C)x^2+(-2B+2C)x+(-4A)}{x(x+2)(x-2)}$ Step 4. Compare the above function with the original to setup the following system of equations: $\begin{cases} A+B+C=0\\-2B+2C=0\\-4A=8 \end{cases}$ Step 5. Solve the above equations: use $A=-2, B=C$ to plug-in the first equation, $-2+2B=0$ or $B=1$, so $C=1$ Step 6. The final result is: $\frac{-2}{x}+\frac{1}{x+2}+\frac{1}{x-2}$ or $\frac{1}{x+2}+\frac{1}{x-2}-\frac{2}{x}$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.