## Elementary Linear Algebra 7th Edition

Since $A^{-1}=\frac{1}{\det(A)}\operatorname{adj}(A)$ , $\det(A)=1$ and the entries of $A$ are integers, then the entries of $A^{-1}$ must be intergers.
Since $A^{-1}=\frac{1}{\det(A)}\operatorname{adj}(A)$ , $\det(A)=1$ and the entries of $A$ are integers, then the entries of $A^{-1}$ must be intergers.