Given A=(2112)A = \begin{pmatrix} 2 & 1 \\ 1 & 2 \end{pmatrix}A=(2112), what are the eigenvectors?
(11)\begin{pmatrix} 1 \\ 1 \end{pmatrix}(11) and (1−1)\begin{pmatrix} 1 \\ -1 \end{pmatrix}(1−1)
(12)\begin{pmatrix} 1 \\ 2 \end{pmatrix}(12) and (21)\begin{pmatrix} 2 \\ 1 \end{pmatrix}(21)
(10)\begin{pmatrix} 1 \\ 0 \end{pmatrix}(10) and (01)\begin{pmatrix} 0 \\ 1 \end{pmatrix}(01)
(1−1)\begin{pmatrix} 1 \\ -1 \end{pmatrix}(1−1) and (00)\begin{pmatrix} 0 \\ 0 \end{pmatrix}(00)