A matrix \(M\) is called invertible if and only if there is a unique matrix \(M^{-1}\) such that
\[ M M^{-1}=M^{-1}M=I, \]where \(I\) denotes the identity matrix .
A matrix \(M\) is called invertible if and only if there is a unique matrix \(M^{-1}\) such that
\[ M M^{-1}=M^{-1}M=I, \]where \(I\) denotes the identity matrix .