Chapter 6, Matrices and Determinants - Section 6.3 - Inverses of Matrices and Matrix Equations - 6.3 Exercises - Page 523: 33

$\left[\begin{array}{c c} 1& 0& 0&0\\ 0& 1/2&0&0\\ 0&0&1/4&0\\0&0&0&1/7\end{array} \right]$

Using a graphing calculator (see attached picture), we get the inverse matrix: $\left[\begin{array}{c c} 1& 0& 0&0\\ 0& 1/2&0&0\\ 0&0&1/4&0\\0&0&0&1/7\end{array} \right]$