[tex]\large\boxed{\begin{array}{l}\tt a)\\\sf a_{11}=1-1=0\\\sf a_{12}=1-2=-1\\\sf a_{21}=2-1=1\\\sf a_{22}=2-2=0\\\sf A=\begin{bmatrix}\sf0&\sf-1\\\sf1&\sf0\end{bmatrix}\\\tt b)~\sf a_{11}=(1+1)^2=4\\\sf a_{12}=(1+2)^2=9\\\sf a_{13}=(1+3)^2=16\\\sf a_{21}=(2+1)^2=9\\\sf a_{22}=(2+2)^2=16\\\sf a_{23}=(2+3)^2=25\\\sf B=\begin{bmatrix}\sf4&\sf9&\sf16\\\sf9&\sf16&\sf25\end{bmatrix}\end{array}}[/tex]
