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

$$ A = \begin{bmatrix} 3 & 7 & 0 \\ 2 & 5 & 0 \\ 5 & 1 & 7 \end{bmatrix} $$
$$ A^{-1}=\begin{bmatrix} 5 & -7 & 0 \\ -2 & 3 & 0 \\ \frac{-23}{7} & \frac{32}{7} & \frac{1}{7} \end{bmatrix} $$

© 2014 Emanuele Santoro