AB=0 but A and B different from 0

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SUMMARY

The discussion centers on proving that if matrix A is not invertible, there exists a non-zero matrix B such that the product AB equals the zero matrix. Participants suggest utilizing the concept of elementary matrices and row-reduced echelon forms to demonstrate this relationship. A key insight is the identification of a nontrivial linear combination of the columns or rows of A that results in zero, indicating the existence of a kernel. This aligns with established linear algebra principles regarding non-invertible matrices.

PREREQUISITES
  • Understanding of linear algebra concepts, particularly matrix invertibility.
  • Familiarity with elementary matrices and their properties.
  • Knowledge of row-reduced echelon forms and their significance in linear transformations.
  • Concept of kernel in vector spaces and its relation to linear combinations.
NEXT STEPS
  • Study the properties of non-invertible matrices in linear algebra.
  • Learn about the role of elementary matrices in matrix transformations.
  • Explore the concept of kernel and image in vector spaces.
  • Investigate nontrivial linear combinations and their implications in solving linear equations.
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Students of linear algebra, educators teaching matrix theory, and anyone interested in understanding the implications of matrix invertibility in mathematical proofs.

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Homework Statement


Need to show that if A is not invertible then exist B (nxn) such that AB=0 but B is different from 0.

Homework Equations



The Attempt at a Solution


Thought about writing A like E1...Ek*R where Ei are elementary matrices and R(different from I) the row reduced echelon matrice but doesn't seem.to help, any idea??
 
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Hint: a nontrivial linear combination of the columns/rows of ##A## is zero.
 
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Likes   Reactions: Anama Skout
Similar to Micromass, write the columns so that they are in the " necessary ( and non-trivial) " kernel.
 

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