Question

Find $x$ and $y$, if $\{3\left[\begin{array}{ccc}1& 2& 0\\ 0& -1& 3\end{array}\right]-\left[\begin{array}{ccc}1& 5& 4\\ -3& -4& 4\end{array}\right]\}\left[\begin{array}{c}1\\ 2\\ 1\end{array}\right]=\left[\begin{array}{c}x\\ y\end{array}\right]$

Answer 1

$\{3\left[\begin{array}{ccc}1& 2& 0\\ 0& -1& 3\end{array}\right]-\left[\begin{array}{ccc}1& 5& 4\\ -3& -4& 4\end{array}\right]\}\left[\begin{array}{c}1\\ 2\\ 1\end{array}\right]=\left[\begin{array}{c}x\\ y\end{array}\right]$

or $\{\left[\begin{array}{ccc}3& 6& 0\\ 0& -3& 9\end{array}\right]-\left[\begin{array}{ccc}1& 5& 4\\ -3& -4& 4\end{array}\right]\}\left[\begin{array}{c}1\\ 2\\ 1\end{array}\right]=\left[\begin{array}{c}x\\ y\end{array}\right]$

or $\left[\begin{array}{ccc}3-1& 6-5& 0-4\\ 0-(-3)& -3-(-4)& 9-4\end{array}\right]\left[\begin{array}{c}1\\ 2\\ 1\end{array}\right]=\left[\begin{array}{c}x\\ y\end{array}\right]$

or $\left[\begin{array}{ccc}2& 1& 4\\ 3& 1& 5\end{array}\right]\left[\begin{array}{c}1\\ 2\\ 1\end{array}\right]=\left[\begin{array}{c}x\\ y\end{array}\right]$

or $\left[\begin{array}{c}2\times 1+1\times 2+(-4\times 1)\\ 3\times 1+1\times 2+5\times 1\end{array}\right]=\left[\begin{array}{c}x\\ y\end{array}\right]$

or $\left[\begin{array}{c}x\\ y\end{array}\right]=\left[\begin{array}{c}0\\ 10\end{array}\right]$