What is the inverse of the matrix M=(2111)M = \begin{pmatrix} 2 & 1 \\ 1 & 1 \end{pmatrix}M=(2111) representing a linear transformation?
(1−1−12)\begin{pmatrix} 1 & -1 \\ -1 & 2 \end{pmatrix}(1−1−12)
(2111)\begin{pmatrix} 2 & 1 \\ 1 & 1 \end{pmatrix}(2111)
(1112)\begin{pmatrix} 1 & 1 \\ 1 & 2 \end{pmatrix}(1112)
(0.5001)\begin{pmatrix} 0.5 & 0 \\ 0 & 1 \end{pmatrix}(0.5001)