Question
If $P=\left[\begin{array}{cc}4 & 6 \\ 2 & -8\end{array}\right], Q=\left[\begin{array}{cc}2 & -3 \\ -1 & 1\end{array}\right]$ Find $2 P Q$
✓
Answer
$\begin{aligned} & P=\left[\begin{array}{cc}4 & 6 \\ 2 & -8\end{array}\right] \\ & Q=\left[\begin{array}{cc}2 & -3 \\ -1 & 1\end{array}\right] \\ & 2 P Q=2\left[\begin{array}{cc}4 & 6 \\ 2 & -8\end{array}\right] \times\left[\begin{array}{cc}2 & -3 \\ -1 & 1\end{array}\right] \\ & =2\left[\begin{array}{cc}8-6 & -12+6 \\ 4+8 & -6-8\end{array}\right] \\ & =2\left[\begin{array}{cc}8 & -6 \\ 12 & -14\end{array}\right] \\ & =\left[\begin{array}{cc}4 & -12 \\ 24 & -28\end{array}\right] .\end{aligned}$
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