x^6=-64 equation
The teacher will be very surprised to see your correct solution 😉
The solution
Detail solution
Given the equation
$$x^{6} = -64$$
Because equation degree is equal to = 6 and the free term = -64 < 0,
so the real solutions of the equation d'not exist
All other 6 root(s) is the complex numbers.
do replacement:
$$z = x$$
then the equation will be the:
$$z^{6} = -64$$
Any complex number can presented so:
$$z = r e^{i p}$$
substitute to the equation
$$r^{6} e^{6 i p} = -64$$
where
$$r = 2$$
- the magnitude of the complex number
Substitute r:
$$e^{6 i p} = -1$$
Using Euler’s formula, we find roots for p
$$i \sin{\left(6 p \right)} + \cos{\left(6 p \right)} = -1$$
so
$$\cos{\left(6 p \right)} = -1$$
and
$$\sin{\left(6 p \right)} = 0$$
then
$$p = \frac{\pi N}{3} + \frac{\pi}{6}$$
where N=0,1,2,3,...
Looping through the values of N and substituting p into the formula for z
Consequently, the solution will be for z:
$$z_{1} = - 2 i$$
$$z_{2} = 2 i$$
$$z_{3} = - \sqrt{3} - i$$
$$z_{4} = - \sqrt{3} + i$$
$$z_{5} = \sqrt{3} - i$$
$$z_{6} = \sqrt{3} + i$$
do backward replacement
$$z = x$$
$$x = z$$
The final answer:
$$x_{1} = - 2 i$$
$$x_{2} = 2 i$$
$$x_{3} = - \sqrt{3} - i$$
$$x_{4} = - \sqrt{3} + i$$
$$x_{5} = \sqrt{3} - i$$
$$x_{6} = \sqrt{3} + i$$
Sum and product of roots
[src]
___ ___ ___ ___
-2*I + 2*I + -I - \/ 3 + I - \/ 3 + \/ 3 - I + I + \/ 3
$$\left(\left(\sqrt{3} - i\right) + \left(\left(\left(- \sqrt{3} - i\right) + \left(- 2 i + 2 i\right)\right) + \left(- \sqrt{3} + i\right)\right)\right) + \left(\sqrt{3} + i\right)$$
$$0$$
/ ___\ / ___\ / ___ \ / ___\
-2*I*2*I*\-I - \/ 3 /*\I - \/ 3 /*\\/ 3 - I/*\I + \/ 3 /
$$- 2 i 2 i \left(- \sqrt{3} - i\right) \left(- \sqrt{3} + i\right) \left(\sqrt{3} - i\right) \left(\sqrt{3} + i\right)$$
$$64$$
$$x_{1} = - 2 i$$
$$x_{2} = 2 i$$
$$x_{3} = - \sqrt{3} - i$$
$$x_{4} = - \sqrt{3} + i$$
$$x_{5} = \sqrt{3} - i$$
$$x_{6} = \sqrt{3} + i$$
x1 = -1.73205080756888 + 1.0*i
x2 = -1.73205080756888 - 1.0*i
x5 = 1.73205080756888 + 1.0*i
x6 = 1.73205080756888 - 1.0*i
x6 = 1.73205080756888 - 1.0*i