1. \displaystyle \frac{1}{9}\begin{pmatrix}4&7&4\\1&4&{-8}\\{-8}&4&1\end{pmatrix}
2. \displaystyle \frac{1}{9}\begin{pmatrix}4&1&{-8}\\7&4&4\\4&{-8}&1\end{pmatrix}.
3. \displaystyle E
