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is-it-125x-3-1-3-a-polynomial-




Question Number 180730 by sciencestudent last updated on 16/Nov/22
is it ((125x^3 ))^(1/3)   a polynomial?
isit125x33apolynomial?
Answered by Frix last updated on 16/Nov/22
No. But for x∈R it is equal to a polynomial:  ((125x^3 ))^(1/3) =5x  Because in R we define ((−r))^(1/3) =−(r)^(1/3)  wherelse  for x∈C we have x=re^(iθ)  and (x)^(1/3) =(r)^(1/3) e^(i(θ/3)) .  in R ((−1))^(1/3) =−(1)^(1/3) =−1  in C ((−1))^(1/3) =(1)^(1/3) e^(i(π/3)) =(1/2)+((√3)/2)i
No.ButforxRitisequaltoapolynomial:125x33=5xBecauseinRwedefiner3=r3wherelseforxCwehavex=reiθandx3=r3eiθ3.inR13=13=1inC13=13eiπ3=12+32i
Commented by MJS_new last updated on 16/Nov/22
you′re right
youreright

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