Need Explination (linear Indpendance)

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Discussion Overview

The discussion revolves around the concept of linear independence in the context of matrices, specifically examining the implications of a zero column in the product of two matrices A and B. The scope includes theoretical exploration and conceptual clarification of linear dependence.

Discussion Character

  • Exploratory
  • Conceptual clarification

Main Points Raised

  • Some participants propose that if the last column of the product AB is entirely zero while B has no zero columns, then the columns of A must be linearly dependent.
  • Questions are raised about the nature of A and B, with one participant asking if they are contravariant vectors and whether AB represents their inner product.
  • Another participant seeks clarification on the representation of entries in the columns of AB and their relation to linear combinations of the columns of A, suggesting that a column of zeros indicates a relationship to linear dependence.

Areas of Agreement / Disagreement

Participants express similar views regarding the linear dependence of columns in A based on the zero column in AB, but there is uncertainty about the definitions and relationships between A and B, indicating unresolved aspects of the discussion.

Contextual Notes

There are limitations in the discussion regarding the definitions of terms such as contravariant vectors and the nature of the product AB, which remain unclear and are not fully resolved.

stuckie27
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A and B are both Matricies,

Suppose the last column of AB is entirely zero but B itself has no column of zeros. What can be said about the columns of A?

Answer: The columns of A are Linearly dependent.

Question: Why?
 
Last edited:
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stuckie27 said:
Suppose the last column o AB is entirely zero but B itself has no column of zeros. What can be said about the columns of A?

Answer: The columns of A are Linearly dependent.

Question: Why?

Are A and B contravariant vecotrs? is AB their inner (scalar) product? If so, I'm not sure how it can have columns, please clarify.
 
edit, A and B are each a different Matrix.
 
take a column in AB, what do the entries represent? are they in some way related to linear combinations of the columns of A? (yes they are, that isn't rhetorical) and a column of zeroes might mean that... fill in the blanks using the definition of linear (in)dependence.
 

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