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Match List-I with List-II

List-IList-II
(Matrix A)(Determinant of adj A)
(A) [2101]\begin{bmatrix} 2 & 1 \\ 0 & -1 \end{bmatrix}(I) 6
(B) [0141]\begin{bmatrix} 0 & 1 \\ 4 & -1 \end{bmatrix}(II) 5
(C) [1231]\begin{bmatrix} 1 & 2 \\ -3 & -1 \end{bmatrix}(III) -4
(D) [4230]\begin{bmatrix} 4 & -2 \\ 3 & 0 \end{bmatrix}(IV) -2

Choose the correct answer from the options given below:

Solution

Correct Option: 4

For any 2×2 matrix A:

det(adj A)=det(A)\text{det(adj A)} = \text{det(A)}

For a 2×2 matrix [abcd]\begin{bmatrix} a & b \\ c & d \end{bmatrix}, the determinant is adbcad - bc.


Matrix A = [2101]\begin{bmatrix} 2 & 1 \\ 0 & -1 \end{bmatrix}

det(A)=(2)(1)(1)(0)\text{det(A)} = (2)(-1) - (1)(0)

det(A)=20\text{det(A)} = -2 - 0

det(A)=2\text{det(A)} = -2

Therefore, det(adj A)=2\text{det(adj A)} = -2, which matches with (IV).


Matrix B = [0141]\begin{bmatrix} 0 & 1 \\ 4 & -1 \end{bmatrix}

det(B)=(0)(1)(1)(4)\text{det(B)} = (0)(-1) - (1)(4)

det(B)=04\text{det(B)} = 0 - 4

det(B)=4\text{det(B)} = -4

Therefore, det(adj B)=4\text{det(adj B)} = -4, which matches with (III).


Matrix C = [1231]\begin{bmatrix} 1 & 2 \\ -3 & -1 \end{bmatrix}

det(C)=(1)(1)(2)(3)\text{det(C)} = (1)(-1) - (2)(-3)

det(C)=1+6\text{det(C)} = -1 + 6

det(C)=5\text{det(C)} = 5

Therefore, det(adj C)=5\text{det(adj C)} = 5, which matches with (II).


Matrix D = [4230]\begin{bmatrix} 4 & -2 \\ 3 & 0 \end{bmatrix}

det(D)=(4)(0)(2)(3)\text{det(D)} = (4)(0) - (-2)(3)

det(D)=0+6\text{det(D)} = 0 + 6

det(D)=6\text{det(D)} = 6

Therefore, det(adj D)=6\text{det(adj D)} = 6, which matches with (I).


The correct matching is:

(A) → (IV)

(B) → (III)

(C) → (II)

(D) → (I)

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