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 570: 108

Answer

$1+i$.

Work Step by Step

The given expression is $=\frac{i^8+i^{40}}{i^4+i^3}$ Factor each term. $=\frac{(i^2)^4+(i^{2})^{20}}{(i^2)^2+i^2i}$ Use $i^2=-1$ $=\frac{(-1)^4+(-1)^{20}}{(-1)^2+(-1)i}$ Simplify. $=\frac{1+1}{1-i}$ $=\frac{2}{1-i}$ The conjugate of the denominator is $1+i$. Multiply the numerator and the denominator by $1+i$. $=\frac{2}{1-i}\cdot \frac{1+i}{1+i}$ Use the special formula $(A+B)^2=A^2+2AB+B^2$ $=\frac{2(1+i)}{1^2-i^2}$ Use $i^2=-1$. $=\frac{2(1+i)}{1+1}$ Simplify. $=\frac{2(1+i)}{2}$ $=1+i$.
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