Examples

Matrix acting on a vector

Matrix acting on a vector

$$\left(\begin{array}{cc}1& 4\\ -2& -1\end{array}\right)\left(\begin{array}{c}3\\ 6\end{array}\right)=\left(\begin{array}{c}1\cdot 3+4\cdot 6\\ -2\cdot 3+-1\cdot 6\end{array}\right)=\left(\begin{array}{c}27\\ -12\end{array}\right)$$