# Talk:Binomial theorem

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 Definition:  ${\displaystyle \textstyle (x+y)^{n}=\sum _{k=0}^{n}{n \choose k}x^{k}y^{n-k}}$ for any natural number n. [d] [e]
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status is really about 2.5 - 2 for the elementary binomial theorem/formula, and 3 for the Newtonian. Anthony Argyriou 17:23, 18 July 2007 (CDT)

While the definition is strictly true, it seems written backwards, in that if you actually do the sum for (x+y)^2 the answer you get as the equation is written is y^2 + 2xy + x^2. Of course you can rearrange to get x^2 + 2xy + y^2. Another way to write it would be

x^(n-k)y^(k), in which case you directly get the answers as shown in the examples.

## popular culture

Can we get rid of the In popular culture section? It adds nothing to anyone's understanding of the binomial theorem. Anthony Argyriou 11:02, 15 July 2008 (CDT)

I agree, so I'll delete it in a minute. -- Jitse Niesen 16:22, 15 July 2008 (CDT)