The product of all eigenvalues of the matrix
| 1 2 3 |
| 4 5 6 |
| 7 8 9 |
is
A. -1
B. 0
C. 1
D. 2
GATE 2024 · Engineering Mathematics · Eigen Value · medium
Answer: Product of all eigenvalues = det(M) = 0. Answer: B
- Check row linear dependence: R2 - R1 = [4-1, 5-2, 6-3] = [3, 3, 3]
R3 - R2 = [7-4, 8-5, 9-6] = [3, 3, 3]
Since R3 - R2 = R2 - R1, we have R3 = 2*R2 - R1. The rows are linearly dependent.
- Conclude determinant equals zero: Since rows are linearly dependent, det(M) = 0. Therefore product of eigenvalues = det(M) = 0.