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QUESTION

Evaluate the product $\textbf{AB}$ of the matrices
$$\textbf{A}=\left(\begin{array}{cc}2&-1\\1&2\end{array}\right),
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\textbf{B}=\left(\begin{array}{ccc}0&1&2\\1&3&1\end{array}\right).$$



ANSWER

$\textrm{AB}=\left(\begin{array}{cc}2&-1\\1&2\end{array}\right)
\left(\begin{array}{ccc}0&1&2\\1&3&1\end{array}\right)=
\left(\begin{array}{ccc}0-1&2-3&4-1\\0+2&1+6&2+2\end{array}\right)=
\left(\begin{array}{ccc}-1&-1&3\\2&7&4\end{array}\right)$





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