The determinant of the matrix is
2000
The determinant of the matrix is

- A.
4
- B.
20
- C.
0
- D.
5
Attempted by 16 students.
Show answer & explanation
Correct answer: A
The correct answer is: 4.
From the image, the matrix is:
[ 2 0 0 0 ]
[ 8 1 7 2 ]
[ 2 0 2 0 ]
[ 9 0 5 1 ]
Expand the determinant along the first row. Since the only non-zero entry in the first row is 2, we get:
det(A) = 2 × det([ [1, 7, 2], [0, 2, 0], [0, 5, 1] ]).
Now compute the 3 × 3 determinant:
det([ [1, 7, 2], [0, 2, 0], [0, 5, 1] ]) = 1(2 × 1 - 0 × 5) = 2.
Therefore:
det(A) = 2 × 2 = 4.