AMO 2023 – Junior College (Grade 11–12) Question 3

Question 3

The vector $\vec a=\begin{pmatrix}2\\4\end{pmatrix}$ is transformed by $M=\begin{pmatrix}0&3\\3&0\end{pmatrix}$. Find $M\vec a$.

1. $\begin{pmatrix}-12\\4\end{pmatrix}$
2. $\begin{pmatrix}12\\6\end{pmatrix}$
3. $\begin{pmatrix}23\\34\end{pmatrix}$
4. $\begin{pmatrix}-16\\8\end{pmatrix}$