Answer
See below
Work Step by Step
Let $\frac{x}{y}A$ be an $n \times n$ matrix with a row (or column).
If any row ( or column ) of $A$ has all of its entries equal to $0$, then there are at least two rows ( or columns ) that are the same, and hence $det ( A ) = 0$ according to P8.
Assume that $A$ has at least one nonzero entry in a row (or column). Then, by adding this row ( or column ) by the row ( or column ) of zeros, we get a matrix $B$ with two equal rows, and by P8 $det ( B ) = 0$.
We can deduce from P3 that $\det ( B ) = \det ( A )$, and thus $\det ( A ) = 0$.
As a result, if a matrix $A$ contains a row (or column) of zeros, $\det ( A ) = 0$.
