Finding nth roots of a complex number

AI Thread Summary
DeMoivre's Theorem is used to find nth roots of complex numbers, which can be raised back to the power of n to return to the original number. The roots are positioned equally around the complex plane, creating a symmetrical distribution. Understanding these roots is essential for various applications, including identifying critical points in complex functions. Additionally, finding roots of real numbers can be important in avoiding certain values in mathematical problems. Overall, the concept of nth roots is foundational in complex analysis and has practical implications in various fields.
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Homework Statement



I have no problem using DeMoivre's Theorem to find nth roots of a complex number. However, I really don't know what this is accomplishing. Usually the book I use explains the concept behind a certain type of problem, but in this case, there is nothing.

I can easily get the correct answer, but I do not know what it means. Any help?

Homework Equations



DeMoivre's Theorem
 
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Well, let us state what the use of these roots are. You can take one of these roots and raise it to the power of n (where n is the number of possible roots) and you will arrive back at the same answer. Also, depending on n, the roots should be positioned equally around the complex plane, with the same angle between each of the roots. This might not explain much, but that's about all I know about the roots =)
 
As well ask why find roots of real numbers? As you go on you will find situations where finding the root of a number is important. Sometimes, it is important knowing where the roots are so as to "avoid them".
 
I tried to combine those 2 formulas but it didn't work. I tried using another case where there are 2 red balls and 2 blue balls only so when combining the formula I got ##\frac{(4-1)!}{2!2!}=\frac{3}{2}## which does not make sense. Is there any formula to calculate cyclic permutation of identical objects or I have to do it by listing all the possibilities? Thanks
Since ##px^9+q## is the factor, then ##x^9=\frac{-q}{p}## will be one of the roots. Let ##f(x)=27x^{18}+bx^9+70##, then: $$27\left(\frac{-q}{p}\right)^2+b\left(\frac{-q}{p}\right)+70=0$$ $$b=27 \frac{q}{p}+70 \frac{p}{q}$$ $$b=\frac{27q^2+70p^2}{pq}$$ From this expression, it looks like there is no greatest value of ##b## because increasing the value of ##p## and ##q## will also increase the value of ##b##. How to find the greatest value of ##b##? Thanks

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