When Does (A+B)(A-B) = A^2 - B^2?

  • Thread starter Thread starter charlies1902
  • Start date Start date
Click For Summary
SUMMARY

The equation (A+B)(A-B) = A^2 - B^2 holds true for n × n matrices A and B when the matrices commute, meaning AB = BA. This conclusion is reached by expanding the left side of the equation and simplifying it to show that the terms cancel out, leading to the requirement that the product of A and B must be equal to the product of B and A. Therefore, the condition for the equality to hold is the commutativity of the matrices involved.

PREREQUISITES
  • Understanding of matrix algebra
  • Familiarity with n × n matrices
  • Knowledge of matrix multiplication properties
  • Concept of matrix commutativity
NEXT STEPS
  • Study the properties of matrix multiplication
  • Explore examples of commuting and non-commuting matrices
  • Learn about matrix identities and their proofs
  • Investigate applications of matrix commutativity in linear transformations
USEFUL FOR

Mathematicians, students studying linear algebra, and anyone interested in advanced matrix theory.

charlies1902
Messages
162
Reaction score
0
If A and B are n × n matrices, when does
(A + B)(A − B) = A^2 − B^2?

I guess I start out by expanding?

A^2 - BA-B^2+BA=0

Thus AB=BA in order for that to work?
 
Physics news on Phys.org
charlies1902 said:
If A and B are n × n matrices, when does
(A + B)(A − B) = A^2 − B^2?

I guess I start out by expanding?

A^2 - BA-B^2+BA=0

Thus AB=BA in order for that to work?

Correct.
 

Similar threads

  • · Replies 40 ·
2
Replies
40
Views
6K
  • · Replies 17 ·
Replies
17
Views
1K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 2 ·
Replies
2
Views
761
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 18 ·
Replies
18
Views
3K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 18 ·
Replies
18
Views
4K
  • · Replies 25 ·
Replies
25
Views
2K