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QUESTION

Evaluate the product \textbf{AB} of the matrices

$$\textbf{A}=\left(\begin{array}{cc}1&amp;-2\\-1&amp;1\end{array}\right),\hspace{1cm}\textbf{B}=\left(\begin{array}{cc}2&amp;-1\\3&amp;1\end{array}\right).$$

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ANSWER


\textbf{AB} $=\left(\begin{array}{cc}1&amp;-2\\-1&amp;1\end{array}\right)
\left(\begin{array}{cc}2&amp;-1\\3&amp;1\end{array}\right)=
\left(\begin{array}{cc}2-6&amp;-1-2\\-2+3&amp;1+1\end{array}\right)=
\left(\begin{array}{cc}-4&amp;-3\\1&amp;2\end{array}\right)$




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