The Eigenvalues Of $A = \left( \begin{array} { c c } 2 & - 1 \\- 1 & 2\end{array} \right)$

Multiple Choice

The eigenvalues of $A = \left( \begin{array} { c c } 2 & - 1 \\- 1 & 2\end{array} \right)$ is

A) $\pm 1$
B) $- 2 \pm i$
C) $2 \pm i$
D) $1,3$
E) $- 1 , - 3$