Square Matrix with Duplicate Rows has Zero Determinant/Corollary

Corollary to Square Matrix with Duplicate Rows has Zero Determinant
If a square matrix has a zero row or zero column, its determinant is zero.

Proof
If you add any row or column to a zero row or zero column, you get a matrix with two identical rows or columns.

From Multiple of Row Added to Row of Determinant, performing this operation does not change the value of the determinant.

So a square matrix with a zero row or column has the same determinant as that with two identical rows or columns.

That is, zero.