Linear dependence of square matrices

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SUMMARY

The discussion centers on the linear dependence of square matrices and the relationship between a matrix and its transpose. It is established that if a square matrix A has linearly dependent columns, then its transpose A^T also has linearly dependent rows. This is supported by the property that the determinant of a matrix is equal to the determinant of its transpose, confirming that the column rank equals the row rank. Therefore, it is impossible to construct a square matrix A with linearly dependent columns while its transpose A^T has linearly independent rows.

PREREQUISITES
  • Understanding of linear dependence and independence in vector spaces
  • Familiarity with square matrices and their properties
  • Knowledge of determinants and their significance in linear algebra
  • Concept of column rank and row rank of matrices
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  • Study the properties of determinants in detail, focusing on square matrices
  • Explore the concepts of column rank and row rank in linear algebra
  • Learn about the implications of linear dependence in higher-dimensional vector spaces
  • Investigate applications of linear dependence in solving systems of linear equations
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Students of linear algebra, mathematicians, and educators seeking to deepen their understanding of matrix theory and linear dependence concepts.

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I am studying the subject of linear dependence right now and had a question on this topic. Is it possible to construct a square matrix A such that the columns of A are linearly dependent, but the columns of the transpose of A are linearly independent? My intuition tells me no, but I'm not sure how I would prove this to be the case in general. I've tried constructing several square matrices that are linearly dependent and taken the transpose and found that to be linearly dependent as well, but I'm not sure if this always holds.
 
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All matrices have the property that the determinant of the transpose is equal to the determinant of the original matrix.

From this I would gather that you can't have the property you have described above.

Look at this site:

http://mathworld.wolfram.com/Determinant.html
 
It's actually stronger than that: the column rank of any matrix (=dimension of space spanned by its columns) equals the row rank. In particular, for square matrices, if the columns are linearly dependent (column rank is smaller than matrix dimension), so are the rows.
 

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