Difference between revisions of "Elementary symmetric sum"
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Revision as of 14:27, 4 January 2008
An elementary symmetric sum is a type of summation.
The -th elmentary symmetric sum of a set of numbers is the sum of all products of of those numbers (). For example, if , and our set of numbers is , then:
1st Symmetric Sum =
2nd Symmetric Sum =
3rd Symmetric Sum =
4th Symmetric Sum =
The first elmentary symmetric sum of is often written . The th can be written
Any symmetric sum can be written as a polynomial of the elmentary symmetric sum functions. For example, . This is often used to solve systems of equations involving power sums, combined with Vieta's.
Elmentary symmetric sums show up in Vieta's formulas. In a monic polynomial, the coefficient of the term is , and the coefficient of the term is .