Answer
These matrices can't be equal.
Work Step by Step
Two matrices are equal if they have the same dimension and
if corresponding elements, position by position, are equal.
---
$\left[\begin{array}{l}
p\\
q\\
r
\end{array}\right]$ is a 3$\times$1 matrix, $\left[\begin{array}{l}
3\\
-9
\end{array}\right]$ is a $2\times 1$ matrix.
They don't have the same dimension, so
these matrices can't be equal.
