1.
If A=[0cbc0aba0]A = \begin{bmatrix}0&c&-b\\-c&0&a\\b&-a&0\end{bmatrix}, B=[a2abacabb2bcacbcc2]B = \begin{bmatrix}a^2&ab&ac\\ab&b^2&bc\\ac&bc&c^2\end{bmatrix}, then AB=AB =