{\left[ {\begin{array}{*{20}c}
 1 & 2 \\
 1 & 0 \\

 \end{array} } \right]} =1\cdot {\left[ {\begin{array}{*{20}c}
 1 & 0 \\
 0 & 0 \\

 \end{array} } \right]} + 2\cdot {\left[ {\begin{array}{*{20}c}
 0 & 1 \\
 0 & 0 \\

 \end{array} } \right]}+ 1\cdot {\left[ {\begin{array}{*{20}c}
 0 & 0 \\
 1 & 0 \\

 \end{array} } \right]}