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Why is (-5)^3=-125 (-5*-5*-5)=-125, 

and 3-th square of (-125) is not defined in real numbers, only in complex numbers? ((-125)^1/3))??? any idea? 

 May 28, 2014

Best Answer 

 #1
avatar+26396 
+15

3-th square of (-125):

3125=3125×31=(5){ei13(π+0π),ei13(π+2π),ei13(π+4π)}3125=(5){ei13π,ei33π,ei53π}3125=(5){ei13π,eiπ,ei53π}eiπ=13125=(5){ei13π,1,ei53π}3125=(5)ei13πcomplex number3125=(5)(1)=5real number 3125=(5)ei53πcomplex number

 May 29, 2014
 #1
avatar+26396 
+15
Best Answer

3-th square of (-125):

3125=3125×31=(5){ei13(π+0π),ei13(π+2π),ei13(π+4π)}3125=(5){ei13π,ei33π,ei53π}3125=(5){ei13π,eiπ,ei53π}eiπ=13125=(5){ei13π,1,ei53π}3125=(5)ei13πcomplex number3125=(5)(1)=5real number 3125=(5)ei53πcomplex number

heureka May 29, 2014

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