What is the inverse of (1001)\begin{pmatrix} 1 & 0 \\ 0 & 1 \end{pmatrix}(1001)?
(1001)\begin{pmatrix} 1 & 0 \\ 0 & 1 \end{pmatrix}(1001)
(0110)\begin{pmatrix} 0 & 1 \\ 1 & 0 \end{pmatrix}(0110)
(−100−1)\begin{pmatrix} -1 & 0 \\ 0 & -1 \end{pmatrix}(−100−1)
(0000)\begin{pmatrix} 0 & 0 \\ 0 & 0 \end{pmatrix}(0000)