Expanding Binomials: Simplifying Complex Expressions

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Homework Statement



by expanding the binomial show that ( (Sqtroot(3)/2) + (1/2)i )^4 = ( (-1/2) + (sqroot(3)/2)i )



The Attempt at a Solution



I'm stuck, I now ( (Sqtroot(3)/2) + (1/2)i )^4 = ( (9/16) + (1/16)i )

But that's all I got, don't know the next steps.
 
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killersanta said:

Homework Statement



by expanding the binomial show that ( (Sqtroot(3)/2) + (1/2)i )^4 = ( (-1/2) + (sqroot(3)/2)i )



The Attempt at a Solution



I'm stuck, I now ( (Sqtroot(3)/2) + (1/2)i )^4 = ( (9/16) + (1/16)i )

But that's all I got, don't know the next steps.

It looks like you are saying that (a + b)4 = a4 + b4. Or that (a + bi)4 = a4 + b4i. Neither is true at all. If you know about the Binomial Theorem you can get the coefficients. For example, (a + b)4 = a4 + 4a3b + 6a2b2 + 4ab3 + b4.

If you don't know about that theorem you can just expand the left side by the square of that binomial, and then multiplying the result by itself. That will give you the fourth power of your binomial.
 
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There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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