Expressing difference product using Vandermonde determinant.

In summary, the conversation discusses a homework problem to show that the function g, defined as g(x_i) = ∏(x_i - x_j), where x=x_n and V_n-1 is the Vandermonde determinant, is equal to (-1)^nV_n-1(x). The solution involves attempting to take a common factor and using sigma notation, with additional help provided in a post linked to the conversation.
  • #1
Adgorn
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Homework Statement


Show that ##g=g(x_1,x_2,...,x_n)=(-1)^{n}V_{n-1}(x)## where ##g(x_i)=\prod_{i<j} (x_i-x_j)##, ##x=x_n## and ##V_{n-1}## is the Vandermonde determinant defined by
##V_{n-1}(x)=\begin{vmatrix}
1 & 1 & ... & 1 & 1 \\
x_1 & x_2 & ... & x_{n-1} & x_n \\
{x_1}^2 & {x_2}^2 & ... & {x_{n-1}}^2 & {x_n}^2 \\
... & ... & ... & ... & ... \\
{x_1}^{n-1} & {x_2}^{n-1} & ... & {x_{n-1}}^{n-1} & {x_n}^{n-1}

\end{vmatrix}##

Homework Equations


N\A

The Attempt at a Solution


After expressing the determinant using the sigma notation I attempted to take a common factor to express it in a similar fashion but to no success. Other than that I really don't know how to approach this (I know I shouldn't say this but it is the case) as I never encountered a proof of this kind, and so I would appreciate some help.
 
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  • #3

Related to Expressing difference product using Vandermonde determinant.

1. What is the Vandermonde determinant?

The Vandermonde determinant is a mathematical concept used to express the difference product of a set of numbers. It is a square matrix with the elements arranged in a specific way, which allows for a quick and efficient calculation of the difference product.

2. How is the Vandermonde determinant calculated?

The Vandermonde determinant is calculated by arranging the elements of the set in a matrix, with the first row containing the elements, the second row containing the elements squared, the third row containing the elements cubed, and so on. The determinant is then calculated using the standard formula for matrix determinants.

3. What is the significance of the Vandermonde determinant?

The Vandermonde determinant has several applications in mathematics and engineering. It is used to solve systems of linear equations, calculate polynomial interpolation, and is also a key component in the Fast Fourier Transform algorithm.

4. Can the Vandermonde determinant be used for any set of numbers?

Yes, the Vandermonde determinant can be used for any set of numbers. However, it is most commonly used for sets of numbers that have a specific pattern, such as consecutive integers or powers of a single number.

5. Are there any limitations to using the Vandermonde determinant?

The main limitation of the Vandermonde determinant is that it can only be used for sets of numbers with distinct values. If there are any repeated elements in the set, the determinant will be zero. Additionally, the calculation of the determinant becomes more complex as the size of the set increases.

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