GATE | GATE-CS-2000 | Question 49

The determinant of the matrix is

(A) 5
(B) 0
(C) 4
(D) 20


Answer: (C)

Explanation: It is a 4*4 matrix, in the first row all elements except 2 are zero so lets find the cofactor for a(0,0).

The cofactor has all zeroes except 1 in its first column so lets find the cofactor of a(1,1).

This turns out to be 2*1 – 6*0 = 2

a(0,0) * a(1,1) * cofactor(a(1,1)) = 2 * 1 *2 = 4

Hence the answer is 4.

This explanation is contributed by Srestha.

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