Matrix Binomials: Struggling to Interpret Question

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Discussion Overview

The discussion revolves around interpreting a mathematical problem involving matrix binomials, specifically focusing on the expression of M^n in terms of matrices X and Y, where M is defined as a combination of these matrices scaled by constants a and b. The scope includes theoretical exploration and mathematical reasoning.

Discussion Character

  • Exploratory
  • Mathematical reasoning

Main Points Raised

  • One participant expresses confusion about the requirements of the problem involving matrices X and Y.
  • Another participant suggests that M can be expressed as M = aX + bY and questions how to expand (aX + bY)^n.
  • A third participant emphasizes the relevance of the title "matrix binomials" in the context of the problem.
  • Another participant proposes diagonalizing the matrix and using the diagonal matrix to compute the nth power, mentioning the application of the binomial theorem for expansion.
  • One participant interprets the request for a general statement as being satisfied by (aX + bY)^n.

Areas of Agreement / Disagreement

Participants have not reached a consensus on the best approach to the problem, and multiple interpretations and methods are being discussed.

Contextual Notes

There may be limitations related to the assumptions about the uniqueness of eigenvalues and orthogonality of eigenvectors when diagonalizing the matrix.

clarex
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Troubles interpreting what this wants from me.

X = (1 1
1 1)

Y = (1 -1
-1 1)

Let A = aX and B = bY, where a and b are constants.

Now consider M= (a+b a-b
a-b a+b)

Find THE general statement that expresses M^n in terms of aX and bY.

I'm completely lost. Can anyone direct me in the right direction?
 
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Okay, so I'm sure you noticed that M = aX + bY. Then M^n = (aX + bY)^n, right? Now, if X and Y were just plain old real numbers (or variables if you like), what would you do to expand (aX + bY)^n
 
Especially since you titled this matrix binomials !
 
Diagonalize the matrix and then take the nth power of the diagonal matrix. You can generally extend scalar functions to matrix functions in this manner provided the eignvalues are unique and the eigenvectors or orthogonal. If you want once you have taken the nth power of the diagonal matrix you can apply the binomial theorem to expand the binomial terms on the diagonal.
 
My interpretation of "Find THE general statement that expresses M^n in terms of aX and bY" is that (aX+ bY)n would be sufficient.
 

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