Precalculus: Mathematics for Calculus, 7th Edition

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

Chapter 8 - Section 8.3 - Polar Form of Complex Numbers; De Moivre's Theorem - 8.3 Exercises - Page 611: 90

Answer

$z_0=cos~\frac{\pi}{12}+i~sin~\frac{\pi}{12}$ $z_1=cos~\frac{5\pi}{12}+i~sin~\frac{5\pi}{12}$ $z_2=cos~\frac{3\pi}{4}+i~sin~\frac{3\pi}{4}=-\frac{\sqrt 2}{2}+\frac{\sqrt 2}{2}i$ $z_3=cos~\frac{13\pi}{12}+i~sin~\frac{7\pi}{12}$ $z_4=cos~\frac{17\pi}{12}+i~sin~\frac{9\pi}{12}$ $z_5=cos~\frac{7\pi}{4}+i~sin~\frac{7\pi}{4}=\frac{\sqrt 2}{2}-\frac{\sqrt 2}{2}i$

Work Step by Step

$z^6-i=0$ $z^6=i$ $r=|i|=1$. Also $i$ lies in the positive real axis. Polar form of $i$: $1(cos~\frac{\pi}{2}+i~sin~\frac{\pi}{2})$ $z_k=\sqrt[6]{1}[cos(\frac{\frac{\pi}{2}+2k\pi}{6})+i~sin(\frac{\frac{\pi}{2}+2k\pi}{6})]$ $z_0=1(cos~\frac{\pi}{12}+i~sin~\frac{\pi}{12})$ $z_1=1(cos~\frac{5\pi}{12}+i~sin~\frac{5\pi}{12})$ $z_2=1(cos~\frac{3\pi}{4}+i~sin~\frac{3\pi}{4})=-\frac{\sqrt 2}{2}+\frac{\sqrt 2}{2}i$ $z_3=1(cos~\frac{13\pi}{12}+i~sin~\frac{7\pi}{12})$ $z_4=1(cos~\frac{17\pi}{12}+i~sin~\frac{9\pi}{12})$ $z_5=1(cos~\frac{7\pi}{4}+i~sin~\frac{7\pi}{4})=\frac{\sqrt 2}{2}-\frac{\sqrt 2}{2}i$
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.