4. Let the four eigenvalues of a square matrix of order 4 be 3,1,1,2, then | a|=

4. Let the four eigenvalues of a square matrix of order 4 be 3,1,1,2, then | a|=

The determinant of a square matrix is equal to the product of all its eigenvalues
So | a | = 3x1x2 = 6