Matrices And Determinants

Consider matrix \(A = \left[ {\matrix{ 2 & 1 \cr 1 & 2 \cr } } \right]\), if \({A^{ - 1}} = \alpha I + \beta A\), where \(\alpha\), \(\beta\) \(\notin\) R, then (\(\alpha\) + \(\beta\)) is equal to (where A^\(-\)1 denotes the inverse of matrix A)