Find all eigenvalues and corresponding eigenvectors for the matrix: $$ \left(\begin{array}{cr} 0&-1 \\ 2&3 \end{array}\right) $$ Not looking for a answer, but I don't know what an "eigenvalue" is or how to find them. Can anyone help me here with a jump off point to get started?

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    $\begingroup$ Do you have a textbook that you are working from? If so, it should at least mention eigenvalues. Here's the wikipedia link: en.wikipedia.org/wiki/Eigenvalues_and_eigenvectors What kind of context are you working in? Simply giving you the answer or simply showing you a technique to find the answer neglects the theory that underpins the concept of an eigenvectors. $\endgroup$
    – Upside
    May 1 '13 at 1:21
  • $\begingroup$ @1ftw1 Make sure you understanding the basic meaning of the terms "eigenvalue" and "eigenvector" before you try to compute them. $\endgroup$ May 1 '13 at 1:53

To compute the eigenvalues solve $det \begin{pmatrix}0-\lambda&-1\\2&3-\lambda\end{pmatrix}=0$. You will get $\lambda=1,2$. These are the two eigenvalues. For each of these you need to solve the system of equations given by $\begin{pmatrix}0-\lambda&-1\\2&3-\lambda\end{pmatrix}\begin{pmatrix}x\\y\end{pmatrix}=\begin{pmatrix}0\\0\end{pmatrix}$. The non-zero solutions are the eigenvectors.

For example with $\lambda=1$ we have the system given by $\begin{pmatrix}-1&-1\\2&2\end{pmatrix}\begin{pmatrix}x\\y\end{pmatrix}=\begin{pmatrix}0\\0\end{pmatrix}$ which has a non zero solution $(1,-1)$.

With $\lambda=2$ we have the system given by $\begin{pmatrix}-2&-1\\2&1\end{pmatrix}\begin{pmatrix}x\\y\end{pmatrix}=\begin{pmatrix}0\\0\end{pmatrix}$ which has a non zero solution $(1,-2)$.

In this way you have found both eigenvalues and a corresponding eigenvector for both.


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