A simple Linear Algebra question that seems so hard

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SUMMARY

The determinant of a matrix changes sign when the columns are reversed, confirming that the statement is sometimes false. This conclusion is derived from the properties of determinants and the cofactor expansion method. Specifically, when applying cofactor expansion to a 3x3 matrix, switching the columns alters the sign of the determinant due to the antisymmetric nature of the determinant function. Understanding this concept is crucial for correctly evaluating determinants in linear algebra.

PREREQUISITES
  • Understanding of matrix operations
  • Familiarity with determinants and their properties
  • Knowledge of cofactor expansion method
  • Basic concepts of linear algebra
NEXT STEPS
  • Study the properties of determinants in linear algebra
  • Learn about cofactor expansion in detail
  • Explore the implications of column operations on determinants
  • Investigate the relationship between matrix transformations and determinant values
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Students studying linear algebra, educators teaching matrix theory, and anyone looking to deepen their understanding of determinants and their properties.

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Homework Statement



Is the statement true or sometimes false. Justify your answer:

The determinant of a matrix is unchanged if the columns are written in reverse order.

Homework Equations





The Attempt at a Solution



I understand that the only thing that is changed is the sign (negative to positive or visa-versa), but do not understand the proof of how.
 
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how do you find the determinant of a matrix?
 
One way would be via cofactor expansion.

I.e. 3x3 matrix determinant =a11C11+a12C12+a13C13
 
okay good. so if you switched the columns, how would the cofactor expansion change?
 
and calculate out those cofactors when you do it.
 

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