[tex]A= \left[\begin{array}{ccc}a_{11}&a_{12}&a_{13}\\a_21}&a_{22}&a_{23}\\a_{31}&a_{32}&a_{33}\end{array}\right] \\
\\
A= \left[\begin{array}{ccc}1^2+1^1&1^2+2^2&1^2+3^2\\2^2+1^2&2^2+2^2&2^2+3^2\\3^2+1^2&3^2+2^2&3^3+3^2\end{array}\right] \\
\\
A= \left[\begin{array}{ccc}2&5&10\\5&8&13\\10&13&18\end{array}\right] [/tex]
