Solving Complex Number Question z^3+i=0 using z^n=|z|^(n) x e^((i)(n)(theta))

Ry122
Messages
563
Reaction score
2
Find z
Question:
z^3+i=0
My attempt:
z^3=-i
use z^n=|z|^(n) x e^((i)(n)(theta))
n = 3
|z|=1
theta = -pie/2
Is this correct?
 
Physics news on Phys.org
if z=i

z^2=-1 z^3=-1*i >>-i
 
… one step at a time …

Ry122 said:
z^3+i=0
My attempt:
z^3=-i
use z^n=|z|^(n) x e^((i)(n)(theta))

Hi Ry122! :smile:

You must be much more logical, or you'll make mistakes. :frown:

Do it one step at a time.

You know z^3=-i.

So - first step - write -i in the form r.e^(i theta).

What is it?

Then divide theta by 3. :smile:

Oh … and how many different solutions are there? :rolleyes:
 
Prove $$\int\limits_0^{\sqrt2/4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx = \frac{\pi^2}{8}.$$ Let $$I = \int\limits_0^{\sqrt 2 / 4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx. \tag{1}$$ The representation integral of ##\arcsin## is $$\arcsin u = \int\limits_{0}^{1} \frac{\mathrm dt}{\sqrt{1-t^2}}, \qquad 0 \leqslant u \leqslant 1.$$ Plugging identity above into ##(1)## with ##u...
Back
Top