Question

Which matrix equation represents the system of equations? {-x+ 2y = 0 y= -2

Answer 1

We are given a system of equations,

$\begin{cases}-x+2y=0\\y=-2\\ \end{cases}$

This will translate into a 2x2 matrix of coefficients (because 2 equations and 2 unknowns),

$\begin{bmatrix}-1&2\\0&1\\ \end{bmatrix}$

The matrix will then be applied to the vector (lower dimensions on top),

$\begin{bmatrix}x\\y\\ \end{bmatrix}$

And the result vector will be whats on the other side of equals sign,

$\begin{bmatrix}0\\-2\\ \end{bmatrix}$

So to put everything together,

$\begin{bmatrix}-1&2\\0&1\\ \end{bmatrix}\begin{bmatrix}x\\y\\ \end{bmatrix}=\begin{bmatrix}0\\-2\\ \end{bmatrix}$

Hope this helps :)