Proving the Binomial Theorem: Simplifying Binomial Coefficients

dalarev
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Homework Statement



Show that binomial coefficients \frac{-1}{n} = (-1)^{n}

Homework Equations



(1+x)^p = (p / n) x^n

The Attempt at a Solution



I'm clueless on the idea of binomial coefficients. I think if I understood the question better I'd know at least where to start. It's not actually -1/n (no division) but I couldn't find the right syntax for it.
 
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I think your equation for (1+x)^p is incomplete. There should be a summation of p+1 terms on the right hand side.

Also, there is a lot of information on binomial coefficients, binomial expansion, and even a formula for generalization to negative numbers on Wikipedia, which should be very helpful.
 
The binomial theorem says that
(a+ b)^n= \sum_{i= 0}^n\left(\begin{array}{c} n \\ i \end{array}\right)a^{n-i}b^i
is that what you mean? And please do not use (p/n) for the binomial coefficient! That's extremely confusing. If you don't want to use LaTex, use nCi.
 
HallsofIvy said:
The binomial theorem says that
(a+ b)^n= \sum_{i= 0}^n\left(\begin{array}{c} n \\ i \end{array}\right)a^{n-i}b^i
is that what you mean? And please do not use (p/n) for the binomial coefficient! That's extremely confusing. If you don't want to use LaTex, use nCi.

yes, that's what I meant. I'm not very experienced with math type on this forum.
 
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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