How to Prove Rank(A) Equals Rank(ATA)?

  • Context: Undergrad 
  • Thread starter Thread starter katyyara
  • Start date Start date
  • Tags Tags
    Matrix rank
Click For Summary
SUMMARY

The discussion focuses on proving the equality of ranks between a matrix A and its product with its transpose, specifically rank(A) = rank(ATA). The key point raised is the challenge in demonstrating that nulity(A) equals nulity(ATA). The proof involves showing that the kernel of A is equivalent to the kernel of ATA, which is a fundamental concept in linear algebra.

PREREQUISITES
  • Understanding of linear algebra concepts, particularly matrix rank and nullity.
  • Familiarity with matrix operations, including transposition and multiplication.
  • Knowledge of kernel and image of a matrix.
  • Basic proficiency in mathematical proofs and logic.
NEXT STEPS
  • Study the properties of matrix rank and nullity in linear algebra.
  • Learn about the kernel of a matrix and its implications in linear transformations.
  • Explore proofs related to the rank-nullity theorem.
  • Investigate the implications of matrix transposition on rank and nullity.
USEFUL FOR

Students and professionals in mathematics, particularly those studying linear algebra, as well as educators looking for clear explanations of matrix properties and proofs.

katyyara
Messages
3
Reaction score
0
Hi,

Does anyone know how to prove rank(A)=rank(AT A) where A is any matrix and AT is the transposed of matrix A? I have difficulty to prove the part that nulity(A)=nulity(AT A). Any help will be appreciated.
 
Physics news on Phys.org
Try proving \operatorname{ker} A = \operatorname{ker} ( A^\top A).
 

Similar threads

  • · Replies 14 ·
Replies
14
Views
3K
  • · Replies 9 ·
Replies
9
Views
5K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 2 ·
Replies
2
Views
4K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 1 ·
Replies
1
Views
9K
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
51K