Abstract: Based on the definition and properties of 2-row n-column determinants, this paper first introduces the definition of 3-row
n-column determinants. On this foundation, it summarizes and proves nine properties of these determinants, then extends them to the general case of m-row n-column determinants. Finally, application examples are provided.

Key words: 3-row n-column determinants, coplanar points, volume of an n-pyramid