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Find all sixth roots of (-64)

 Jan 8, 2016
edited by gibsonj338  Jan 8, 2016

Best Answer 

 #2
avatar+118696 
+5

Hi Gibsonj335,

 

 

Find all sixth roots of (-64)

the first one is 2i     this has no real part so it is on the imaginary axis.   it is    2eiπ/2

 

the difference in the angles (arguments) is going to be  2pi/6 

 

 

 

the angles will be

 

So the first angle is pi/2 which equals  3pi/6

 

the angles (arguments)  will be

 

 3π6,3π+2π6,3π+4π6,3π+6π6,3π+8π6,3π+10π6 3π6,5π6,7π6,9π6,11π6,13π6 so the 6 roots will be: 2e3πi6,2e5πi6,2e7πi6,2e9πi6,2e11πi6,2e13πi6 

I wasn't sure of the working so I used this for a reference:

 

http://tutorial.math.lamar.edu/Extras/ComplexPrimer/Forms.aspx

 Jan 8, 2016
 #1
avatar
+5

2 e^((i pi)/6)~~1.7321+1.0000 i  (principal root)

2 i

2 e^((5 i pi)/6)~~-1.7321+1.000 i

-2 i

2 e^(-(5 i pi)/6)~~-1.7321-1.000 i

2 e^(-(i pi)/6)~~1.7321-1.0000 i

 Jan 8, 2016
 #2
avatar+118696 
+5
Best Answer

Hi Gibsonj335,

 

 

Find all sixth roots of (-64)

the first one is 2i     this has no real part so it is on the imaginary axis.   it is    2eiπ/2

 

the difference in the angles (arguments) is going to be  2pi/6 

 

 

 

the angles will be

 

So the first angle is pi/2 which equals  3pi/6

 

the angles (arguments)  will be

 

 3π6,3π+2π6,3π+4π6,3π+6π6,3π+8π6,3π+10π6 3π6,5π6,7π6,9π6,11π6,13π6 so the 6 roots will be: 2e3πi6,2e5πi6,2e7πi6,2e9πi6,2e11πi6,2e13πi6 

I wasn't sure of the working so I used this for a reference:

 

http://tutorial.math.lamar.edu/Extras/ComplexPrimer/Forms.aspx

Melody Jan 8, 2016

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