Precalculus (10th Edition)

Published by Pearson
ISBN 10: 0-32197-907-9
ISBN 13: 978-0-32197-907-0

Appendix A - Review - A.7 Complex Numbers; Quadratic Equations in the Complex Number System - A.7 Assess Your Understanding - Page A61: 38

Answer

$i$

Work Step by Step

Use the exponent rule $a^{-b}=\frac{1}{a^b}$. $i^{-23}\\ \\=\dfrac{1}{i^{23}}$ $=\dfrac{1}{i^{22}\cdot i}$ $=\dfrac{1}{i^{2(11)}\cdot i}$ $=\dfrac{1}{(i^{2})^{11}\cdot i}$ Use $i^2=-1$. $=\dfrac{1}{(-1)^{11}\cdot i}$ $=\dfrac{1}{-1\cdot i}$ $=\dfrac{1}{-i}$ Multiply both the numerator and the denominator by the conjugate of $-i$ which is $i$. $=\dfrac{1}{-i}\cdot \dfrac{i}{i}$ Simplify. $=\dfrac{i}{-i^2}$ Use $i^2=-1$. $=\dfrac{i}{-(-1)}$ $=\dfrac{i}{1}$ $=i$ Hence, the solution in the standard form is $i$.
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