De Moivre's theorem HELP~

  • #1
De Moivre's theorem~~HELP~

Homework Statement



Solve the following equations


z^3=-8i


Can anyone plz tell me how to solve this problem?
 

Answers and Replies

  • #2
Mentallic
Homework Helper
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You can use De Moivre's theorem (actually, are you meant to?) but there is an easier way to solve it.

Notice that [tex]-8i=\left(2i\right)^3[/tex]
 
  • #3
108
0


Homework Statement



Solve the following equations


z^3=-8i


Can anyone plz tell me how to solve this problem?

Z=cuberoot(-8i)

So write (-8i) in r*e^(i*theta) form and then raise it to the one-third...then consider all the angles that theta could be as you round the unit circle once.

EDIT: I like Mentallic's way, haha.
 
  • #4
Mentallic
Homework Helper
3,798
94

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