Question

The graph shows a reflection in the y-axis. The matrix M such that, for any point (x, y), M(x, y) = (x', y') is

Answer 1

`\text{A)}\quad\left[\begin{array}{cc}-1&0\\0&1\end{array}\right]`

Explanation:

Reflection across the y-axis negates the x-coordinate. The y-coordinate stays the same. The first matrix does that: selection A.