Find Eigenvalues & Eigenspace for (3,0) (8,-1) Matrix | Homework Statement

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In summary: You get a matrix with all zeros on the last column. That means that the last column is a free variable. So you can choose whatever value you want for v2. So the eigenvector is [0, v2] where v2 is any number.In summary, for the given matrix, the eigenvalues are -1 and 3, and the corresponding eigenvectors are [0,v2] and [v1, 2v1], where v1 and v2 are any real numbers.
  • #1
Chewybakas
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Homework Statement


Find the eigenvalues and eigenspace of the given vector.

Homework Equations


Matrix = (3,0)
(8,-1)

The Attempt at a Solution


I have determined the eigenvalues to be -1 and 3, but when I try compute the eigenspace when lambda = -1 I constantly get confused and end up with the space equal to span(t[0,0]) tεℝ. Can anyone help or confirm that answer!
 
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  • #2
I agree with the eigenvalues. Can you show your computations for the eigenspace for ##\lambda = -1##?
 
  • #3
Chewybakas said:

Homework Statement


Find the eigenvalues and eigenspace of the given vector.


Homework Equations


Matrix = (3,0)
(8,-1)


The Attempt at a Solution


I have determined the eigenvalues to be -1 and 3, but when I try compute the eigenspace when lambda = -1 I constantly get confused and end up with the space equal to span(t[0,0]) tεℝ. Can anyone help or confirm that answer!

What are the equations you get when you try to find the eigenvectors for λ = -1?
 
  • #4
I reduced the original matrix to reduced row echelon form which gave me the identity 2x2 matrix, which when finding two values v1,v2 where when multiplied by the identity matrix gives zero, I get the answer stated above but when i tried a different way I get the eigenspace 2v1 and 9v1 which again confuses me.
 
  • #5
Chewybakas said:
I reduced the original matrix to reduced row echelon form which gave me the identity 2x2 matrix, which when finding two values v1,v2 where when multiplied by the identity matrix gives zero, I get the answer stated above but when i tried a different way I get the eigenspace 2v1 and 9v1 which again confuses me.

That's not how it works.

For λ = -1, you are solving the equation (A - λI)x = 0
For this eigenvalue, A - λI is
$$ \begin{bmatrix} 4 & 0 \\ 8 & 0\end{bmatrix}$$

When you row reduce this you DON'T get the identity matrix.
 

1. What is a matrix eigenspace?

A matrix eigenspace is the set of all eigenvectors corresponding to a particular eigenvalue of a matrix. In other words, it is the subspace of the original vector space that is transformed only by a scalar factor when multiplied by the matrix.

2. How do I find the eigenspace of a matrix?

To find the eigenspace of a matrix, you first need to find the eigenvalues of the matrix. Then, for each eigenvalue, you can find the corresponding eigenvectors by solving the equation (A - λI)x = 0, where A is the original matrix, λ is the eigenvalue, and x is the eigenvector. The set of all these eigenvectors will make up the eigenspace.

3. Why is the eigenspace important?

The eigenspace is important because it provides a way to break down a matrix into simpler components. This can be useful in solving systems of linear equations, diagonalizing matrices, and understanding the behavior of linear transformations.

4. Can a matrix have multiple eigenspaces?

Yes, a matrix can have multiple eigenspaces. Each eigenvalue will have its own corresponding eigenspace, and it is possible for multiple eigenvalues to have the same eigenspace.

5. How is the dimension of the eigenspace related to the multiplicity of an eigenvalue?

The dimension of the eigenspace is equal to the multiplicity of the eigenvalue. In other words, the number of linearly independent eigenvectors corresponding to an eigenvalue is equal to its multiplicity.

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