Which of the following matrices have complex (non-real) eigenvalues?
(0−110)\begin{pmatrix} 0 & -1 \\ 1 & 0 \end{pmatrix}(01−10)
(1221)\begin{pmatrix} 1 & 2 \\ 2 & 1 \end{pmatrix}(1221)
(300−2)\begin{pmatrix} 3 & 0 \\ 0 & -2 \end{pmatrix}(300−2)
(2112)\begin{pmatrix} 2 & 1 \\ 1 & 2 \end{pmatrix}(2112)