Linear Algebra Similar Matrices Problem

In summary, the conversation discusses finding two 2x2 matrices A and B that are not similar to each other. The hint suggests that if AB=0 and BA is not zero, then they are not similar. The person attempting the problem mentions trying to solve it through guess and check, but has been unsuccessful.
  • #1
SuperZero
1
0

Homework Statement



Find two 2 × 2 matrices A and B such that AB fails to be similar to
BA. Hint: it can be arranged that AB is zero but BA is not.


Homework Equations



N/A


The Attempt at a Solution



If AB similar to BA, AB = S-1BAS for some S, so AB DNE S-1BAS?
Or maybe det(AB) DNE det(BA)
I'm really not sure how to do this without guess and check, which I also tried and failed at
 
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  • #2
You aren't paying much attention to the hint. If AB=0 and BA is not zero, then they aren't similar. Look for a example of that.
 

1. What is a similar matrix in linear algebra?

A similar matrix in linear algebra is a matrix that has the same eigenvalues as another matrix. This means that the two matrices represent the same linear transformation, but with respect to different bases.

2. How do you know if two matrices are similar?

Two matrices are similar if they have the same eigenvalues. This can be determined by calculating the characteristic polynomial of each matrix and comparing their roots.

3. What is the importance of similar matrices in linear algebra?

Similar matrices have many important applications in linear algebra, including finding the diagonal form of a matrix, solving systems of linear equations, and determining the behavior of linear transformations.

4. How do you solve problems involving similar matrices?

To solve problems involving similar matrices, you can use various techniques such as diagonalization, finding the Jordan canonical form, or using the Cayley-Hamilton theorem.

5. Can two matrices be similar if they have different dimensions?

No, two matrices must have the same dimension to be considered similar. This is because the eigenvalues of a matrix are determined by its size, and if two matrices have different dimensions, they will have different eigenvalues.

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