[tex]\left[\begin{array}{cc}1&2\\4&1\end{array}\right] +2* \left[\begin{array}{ccc}0&x\\y&0\end{array}\right] = \left[\begin{array}{ccc}1&0\\0&1\end{array}\right]
[/tex]
[tex]\left[\begin{array}{cc}1&2\\4&1\end{array}\right] + \left[\begin{array}{ccc}0&2x\\2y&0\end{array}\right] = \left[\begin{array}{ccc}1&0\\0&1\end{array}\right] [/tex]
[tex]\left[\begin{array}{cc}1&2+2x\\4+2y&1\end{array}\right] = \left[\begin{array}{ccc}1&0\\0&1\end{array}\right] [/tex]
[tex]2+2x=0 =\ \textgreater \ x=-1[/tex]
[tex]4+2y=0=\ \textgreater \ y=-2[/tex]