Math 2.0

Linear and multilinear algebra; matrix theory Proof

Proof that a matrix with two equal rows has determinant zero

Builds on Determinant

Proof

  1. Let AA be an n×nn \times n matrix over KK with rows i≠ji \ne j that are equal.
  2. By property 2 of the definition of the determinant, det⁡\det vanishes on every matrix with two equal rows.
  3. So det⁡A=0\det A = 0.

Idea

In this course the determinant is defined as the unique alternating multilinear function of the rows with value 11 on the identity. Vanishing on two equal rows is the alternating property, so the claim is part of the definition.

Reading path

To understand this page from the ground up, read these 9 pages in order. The foundations come first.

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Each page uses the pages above it. The colour of the bar on a box shows how strong the evidence is, and the box also gives it as text. The list has the same pages.
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  1. Identity matrix object
  2. Matrix definition
  3. Vector space definition
  4. Square matrix definition
  5. Linear map definition
  6. Multilinear map definition
  7. Alternating multilinear map definition
  8. Determinant definition
  9. Proof that a matrix with two equal rows has determinant zero proof

Where this leads

250 pages build on this one.

Further reading

  1. Web https://en.wikipedia.org/wiki/Determinant, As an alternating multilinear form
About this page
Tag9WQHK4Z2WD
URIm2://9WQHK4Z2WD
Kindproof
WritingW0 stub
MSC15A15
ProvesDeterminant of a matrix with two equal rows
UsesDeterminant
Changed4 November 2026

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