Construct a random integer-valued 4x4 matrix A.
Use Excel and the function MDETERM to calculate the determinant of A. If A is not invertible, choose another A.
Reduce A to echelon form U with no row scaling.
Use the formula det A = {(-1)^r (product of the pivots in U) when A is invertible / 0 when A is not invertible, where r is the number of row exchanges to calculate the determinant of A.
Compute the eigenvalues of A and the product of these eigenvalues (as accurately as possible).
List the matrix A, and to 4 decimal places, list the pivots in U and the eigenvalues of A. Compare the determinant of A with the products you found above.