Invertible Matrices with det=1 & Integer Entries: Why Inverse is Integer?

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SUMMARY

An invertible matrix A with a determinant of 1 and all integer entries guarantees that its inverse also contains only integer entries. This is a consequence of the properties of determinants and integer matrices, specifically that the determinant being 1 implies that the matrix is unimodular. The inverse can be computed using the adjugate matrix and the determinant, which preserves the integer nature of the entries.

PREREQUISITES
  • Understanding of matrix theory and properties of determinants
  • Familiarity with integer matrices and their characteristics
  • Knowledge of the adjugate matrix and its role in finding inverses
  • Basic linear algebra concepts, including invertibility
NEXT STEPS
  • Study the properties of unimodular matrices in linear algebra
  • Learn about the computation of the adjugate matrix and its applications
  • Explore the implications of integer matrices in modular arithmetic
  • Investigate the relationship between determinants and matrix inverses
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Students and professionals in mathematics, particularly those studying linear algebra, matrix theory, and applications involving integer matrices.

bodensee9
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Can someone explain why if an invertible matrix A has det = 1 and all integer entries, its inverse also has all integer entries? det(A) = 1 means that if you apply the big formula (permutations) the sums of the entries add up to 1. But what does that have to with having integers in its inverse?

Thanks.
 
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never mind, figured it out. thanks.
 

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