A community for students. Sign up today!
Here's the question you clicked on:
 0 viewing
 one year ago
please help me i have some idea of what to do but i need help !
use de moivre's theorem to solve each of these questions. plot your solutions on the complex plain.
(i) z^3 = 8
 one year ago
please help me i have some idea of what to do but i need help ! use de moivre's theorem to solve each of these questions. plot your solutions on the complex plain. (i) z^3 = 8

This Question is Closed

phi
 one year ago
Best ResponseYou've already chosen the best response.0I think they want you to write 8 as \[ 8=8(\cos(2 \pi) + i \sin(2 \pi))\]

samnatha
 one year ago
Best ResponseYou've already chosen the best response.0well the theorm we have been using is diff cuz u have to add 2n(pi)

phi
 one year ago
Best ResponseYou've already chosen the best response.0yes, that is even better. 8=8(cos(2nπ)+isin(2nπ))

samnatha
 one year ago
Best ResponseYou've already chosen the best response.0like the way our teacher has been telling us is we have to get this \[\sqrt[3]{8?}\]

samnatha
 one year ago
Best ResponseYou've already chosen the best response.0then it is 2 to the power of a third

phi
 one year ago
Best ResponseYou've already chosen the best response.0See http://en.wikipedia.org/wiki/De_Moivre's_formula#Applications you solve \[ \left( z^3 \right)^{\frac{1}{3}} = 8^{\frac{1}{3}}(\cos(2n\pi)+i \sin(2n\pi)^{\frac{1}{3}}\]

phi
 one year ago
Best ResponseYou've already chosen the best response.0you get 3 different answers, for n=0,1,2. then they start repeating n=3 gives the same answer as n=0

samnatha
 one year ago
Best ResponseYou've already chosen the best response.0yeah i kinda get thanks

samnatha
 one year ago
Best ResponseYou've already chosen the best response.0wait usually ther is another angle you can't get 0 of 2n pi

phi
 one year ago
Best ResponseYou've already chosen the best response.0in case it is not clear 8 = 8( cos(0) + i sin(0)) when we add in multiples of 2π we get 8 = 8( cos(2nπ ) + i sin(2nπ))
Ask your own question
Ask a QuestionFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.