minant of order n is expanded as a function of determinants of one less order. Each of these determinants, in turn, is expanded as a linear function of determinants of order (n-2). This substitution of determinants of one less order continues until |A| is expressed in terms of determinants of 2×2 submatrices of A.
The first step of the expansion is illustrated for a 3×3 matrix A. To compute the determinant of A, choose any row or column of the matrix. For each element of the row or column chosen, compute the cofactor of the element. Then, if the ith row of A is used for the expansion,