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Complex number help

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Monopoly:
help me to solve this question:

the roots of the equation
                                        z2+ 2z+4=0
are denoted by a and b. Find a and b in the form reitheta, giving the exact values of r and theta.

for the theta of reitheta, does the range -pie<theta=<pie still applies?

elemis:
The easiest method to solve this is to simply solve the quadtratic equation as it is is given.

Thus the roots are  and

I guess you want those in modulus-argument form ?

Therefore it should be :

2(cos 2pi/3 + i sin 2pi/3)

2(cos -2pi/3 + i sin -2pi/3)

Monopoly:

--- Quote from: Ari Ben Canaan on November 16, 2010, 01:48:29 pm ---The easiest method to solve this is to simply solve the quadtratic equation as it is is given.
Thus the roots are  and
I guess you want those in modulus-argument form ?
Therefore it should be :
2(cos 2pi/3 + i sin 2pi/3)
2(cos -2pi/3 + i sin -2pi/3)

--- End quote ---

the asked modulus form is bugging me,   ???
the ans given is 2ei(2pie/3) & 2ei(4pie/3)

astarmathsandphysics:
One hour

astarmathsandphysics:
To change into polar form
2(cos 2pi/3 + i sin 2pi/3) =2cos 2pi/3 +2isin 2pi/3
R=sqrt((2cos 2pi/3)^2+(2sin 2pi/3)^2) =2 ang arg =2pi/3 etc

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