Look at this matrix. Is it invertible? If so, try compute the inverse.

$$ A = \begin{bmatrix} -1 & 0 & -1 \\ 6 & -1 & 3 \\ 6 & 3 & -1 \end{bmatrix} $$
$$ A^{-1}=\begin{bmatrix} \frac{1}{2} & \frac{3}{16} & \frac{1}{16} \\ \frac{-3}{2} & \frac{-7}{16} & \frac{3}{16} \\ \frac{-3}{2} & \frac{-3}{16} & \frac{-1}{16} \end{bmatrix} $$

© 2014 Emanuele Santoro