Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 7 - Section 7.7 - Complex Numbers - Exercise Set - Page 572: 141

Answer

$\frac{14}{25}-\frac{2}{25}i$.

Work Step by Step

The given expression is $=\frac{4}{(2+i)(3-i)}$ Use the FOIL method. $=\frac{4}{6-2i+3i-i^2}$ Use $i^2=-1$. $=\frac{4}{6-2i+3i+1}$ Add like terms. $=\frac{4}{7+i}$ The conjugate of the denominator is $7-i$. Multiply the numerator and the denominator by $7-i$. $=\frac{4}{7+i}\cdot \frac{7-i}{7-i}$ Use the special formula $(A+B)^2=A^2+2AB+B^2$ $=\frac{28-4i}{7^2-i^2}$ Use $i^2=-1$. $=\frac{28-4i}{49+1}$ Simplify. $=\frac{28-4i}{50}$ Rewrite as $a+ib$. $=\frac{28}{50}-\frac{4}{50}i$ Simplify. $=\frac{14}{25}-\frac{2}{25}i$.
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.