The fourth-order determinant * * * has 24 terms, including 6 terms for the factor a 1 1 and 6=3 terms for the factor a23! Item 2 (4-2) and item a 1 1 and a23! =2! Project. Since the two items belong to 1 row 1 column and 2 rows and 3 columns, only 3 rows and 2 columns, 3 rows and 4 columns, 4 rows and 4 columns are merged. Because elements in the same row or column will not appear in the same item, there are only two combinations of a32a44 and a34a42, and the corresponding item with symbols ignored is A11a.

. However, according to the reverse order test, the sign of a1/a23a32a44 is negative, that is, the term containing the factor a 1 1a23 is:

-a11a23a44 and a 1 1a23a34a42.