Chapter 9.3, Problem

In Problem 9-14, use the method of Example 1 to compute the inverse of the given matrix, if exists. For problem 9 and 10 confirm your answer by comparison with formula (3).

$\left[\begin{array}{ccc}1& 1& 1\\ 1& -1& 2\\ 1& 1& 4\end{array}\right]$