If $A$ is a square matrix that satisfies $A^2-A+2I=0$, show that $A+I$ is invertible If $A$ is a square matrix that satisfies $A^2-A+2I=0$, show that $A+I$ is invertible. I understand how to find if $A$ is invertible but I don't know how to solve for the $A+I$ version.

$(A+I)(A-2I)=A^2-2A+A-2I=A^2-A-2I=-4I$
