Proving Unique Decomposition of a Square Matrix

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Homework Help Overview

The discussion revolves around the unique decomposition of a square matrix into symmetric and skew-symmetric components. The original poster presents a statement regarding an nxn matrix and seeks to prove the decomposition A = B + C, where B is symmetric and C is skew-symmetric.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the properties of (A + A^T) and (A - A^T), identifying one as symmetric and the other as skew-symmetric. There is uncertainty about how to utilize this information effectively in the context of the problem.

Discussion Status

The conversation is ongoing, with some participants providing guidance on manipulating the identified expressions. There is a recognition of the relationship between the components, but no consensus has been reached on the next steps or the overall proof.

Contextual Notes

Participants express confusion regarding the implications of their findings and the requirements for the proof, indicating a need for further clarification on the decomposition process.

mlarson9000
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Homework Statement



An nxn matrix C is skew symmetric if C^t = -C. Prove that every square matrix A can be written uniquely as A = B + C where B is symmetric and C is skew symmetric.


Homework Equations





The Attempt at a Solution



No clue.
 
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You aren't trying very hard, now are you? Tell me about (A+A^T) and (A-A^T). Are they symmetric, skew-symmetric or neither? You have to help here.
 
(A+A^T)is symmetric, (A-A^T)is skew symmetric, but adding them together produces 2A, not A. I'm not sure what to do with this information.
 
mlarson9000 said:
(A+A^T)is symmetric, (A-A^T)is skew symmetric, but adding them together produces 2A, not A. I'm not sure what to do with this information.

That's not such a big problem. Divide each one by two.
 
Dick said:
That's not such a big problem. Divide each one by two.

How embarrassing.
 

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