Chapter A.3, Problem 7P

In each of Problems 1 through 10, use elementary row and column operations to simplify the task of evaluating the determinant by cofactor expansions. If $\text{A}$ is nonsingular, find ${\text{A}}^{-1}$.

$\text{A}\text{=}\left(\begin{array}{ccc}1& 1& -1\\ 2& 1& 0\\ 3& -2& 1\end{array}\right)$