Transposing and Inversing Matrices

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SUMMARY

The discussion centers on proving that if matrix A is invertible, then both A*AT and AT*A are also invertible. Key equations referenced include (AT)-1=(A-1)T and (AB)T=ATBT. The participants emphasize the importance of understanding matrix multiplication and the properties of transposition in relation to invertibility. The challenge lies in applying these properties to demonstrate the invertibility of the products A*AT and AT*A.

PREREQUISITES
  • Understanding of matrix operations, specifically multiplication and transposition.
  • Familiarity with the concept of matrix inverses and the identity matrix.
  • Knowledge of linear algebra principles, particularly regarding invertible matrices.
  • Proficiency in applying mathematical proofs in linear algebra.
NEXT STEPS
  • Study the properties of matrix transposition in detail.
  • Learn about the implications of matrix invertibility in linear transformations.
  • Explore examples of proving the invertibility of matrix products.
  • Investigate the relationship between eigenvalues and matrix invertibility.
USEFUL FOR

Students of linear algebra, mathematicians, and educators looking to deepen their understanding of matrix properties and proofs related to invertibility.

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Homework Statement


Prove that if A is an invertible matrix, then A*AT and AT*A are also invertible.


Homework Equations


(AT)-1=(A-1)T
(AB)T=ATBT

The Attempt at a Solution


I just can't wrap my brain around this one. I know that I have to multiply a matrix by its inverse to get the identity matrix, but I don't know where to go from there.
 
Physics news on Phys.org
(AB)^T=B^T*A^T. Not A^T*B^T. Now that we've gotten past that, what would be the inverse of A*A^T given both of the elements in the product have inverses?
 

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