Similar Matrices: Showing A Not Similar to B

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In summary, to show that matrix A is NOT similar to matrix B, you can either demonstrate that B is not equal to the inverse of any matrix P multiplied by A and then multiplied by P, or you can show that they do not share the same eigenvalues and corresponding eigenvectors.
  • #1
cutesteph
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Homework Statement


A=[a,1;0,a] B=[a,0;0,a]
If I want to show if matrix A is NOT similar to matrix B. Is it enough to show that B=/=Inv(P)*A*P? Or would I need to show that they do not have both the same eigenvalues and corresponding eigenvectors?
 
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  • #2
cutesteph said:

Homework Statement


A=[a,1;0,a] B=[a,0;0,a]
If I want to show if matrix A is NOT similar to matrix B. Is it enough to show that B=/=Inv(P)*A*P? Or would I need to show that they do not have both the same eigenvalues and corresponding eigenvectors?

It would be enough to show B=/=Inv(P)*A*P for any invertible matrix P, if you have a clever way to do that. But I think the eigenvalue/eigenvector approach is more straightforward. If you calculate those for each matrix what do you get?
 

Related to Similar Matrices: Showing A Not Similar to B

1. What is the definition of similar matrices?

Similar matrices are square matrices that have the same dimensions and share the same geometric properties. This means that they can be transformed into each other through a change of basis, resulting in the same linear transformation.

2. How can I determine if two matrices are similar?

To determine if two matrices are similar, you can check if they have the same dimensions and if they have the same eigenvalues. If their eigenvalues are the same, then they are similar. However, if even one eigenvalue is different, then the matrices are not similar.

3. Can two matrices with different entries be similar?

No, two matrices with different entries cannot be similar. Similar matrices must have the same entries in the same positions, but they may have different scalar multiples of each other.

4. What is the importance of showing that two matrices are not similar?

Showing that two matrices are not similar is important because it helps us understand the underlying linear transformations and properties of each matrix. It also allows us to determine if a certain transformation is unique to a specific matrix.

5. Is there a quick way to prove that two matrices are not similar?

Yes, there is a quick way to prove that two matrices are not similar. You can show that the matrices have different determinants or different ranks. If the determinants or ranks are different, then the matrices are not similar.

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