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Determinati nr reale x si y,stiind ca A+2B=I2,unde I2=(1 0 0 1)
Matricea A=( 1 2 4 1) si B( 0 x y 0)


Răspuns :

[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]