If the matrix $A$ is such that $$A = \begin{bmatrix} 2 \\ -4 \\ 7 \end{bmatrix} \begin{bmatrix} 1 & 9 & 5 \end{bmatrix}$$ then the determinant of $A$ is equal to _________.

Matrix $A$ is formed by multiplying a column vector $u = \begin{bmatrix} 2 \\ -4 \\ 7 \end{bmatrix}_{3 \times 1}$ with a row vector $v^T = \begin{bmatrix} 1 & 9 & 5 \end{bmatrix}_{1 \times 3}$.

The resulting matrix $A$ has dimensions $3 \times 3$:

Since $A$ is the outer product of two non-zero vectors, its rank is at most $1$.

For a $3 \times 3$ matrix with $\text{rank}(A) = 1 < 3$, the matrix is singular, and therefore its determinant is: