# De Moivre's theorem HELP~

littlewombat
De Moivre's theorem~~HELP~

## Homework Statement

Solve the following equations

z^3=-8i

Can anyone plz tell me how to solve this problem?

Homework Helper

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

Notice that $$-8i=\left(2i\right)^3$$

Apphysicist

## 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.

Homework Helper

EDIT: I like Mentallic's way, haha.

Haha thanks