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)