Target Exam

CUET

Subject

-- Applied Mathematics - Section B2

Chapter

Question:

Match List-I with List-II

List-I (Matrix A)

List-II (Determinant of Adjoint of A)

(A) $\begin{bmatrix}3&1\\4&2
\end{bmatrix}$

(I) 9

(B) $\begin{bmatrix}5&-1\\4&2
\end{bmatrix}$

(II) 8

(C) $\begin{bmatrix}6&-1\\2&1
\end{bmatrix}$

(III) 14

(D) $\begin{bmatrix}4&1\\3&3
\end{bmatrix}$

(IV) 2

Choose the correct answer from the options given below:

Options:

(A)-(I), (B)-(II), (C)-(III), (D)-(IV)

(A)-(II), (B)-(I), (C)-(III), (D)-(IV)

(A)-(III), (B)-(IV), (C)-(II), (D)-(I)

(A)-(IV), (B)-(III), (C)-(II), (D)-(I)

Correct Answer:

(A)-(IV), (B)-(III), (C)-(II), (D)-(I)

Explanation:

The correct answer is Option (4) → (A)-(IV), (B)-(III), (C)-(II), (D)-(I)

List-I (Matrix A)

List-II (Determinant of Adjoint of A)

(A) $\begin{bmatrix}3&1\\4&2
\end{bmatrix}$

(IV) 2

(B) $\begin{bmatrix}5&-1\\4&2
\end{bmatrix}$

(III) 14

(C) $\begin{bmatrix}6&-1\\2&1
\end{bmatrix}$

(II) 8

(D) $\begin{bmatrix}4&1\\3&3
\end{bmatrix}$

(I) 9

Given: Determinant of adj(A) for a 2×2 matrix is given by:

$\det(\text{adj}(A)) = (\det(A))^{n-1}, \; n=2 \;\;\Rightarrow\;\; \det(\text{adj}(A)) = \det(A)$

Now, compute determinants:

(A) $A=\begin{bmatrix}3 & 1 \\ 4 & 2\end{bmatrix}, \;\det(A)=3(2)-1(4)=6-4=2$ $\;\;\Rightarrow \det(\text{adj}(A))=2$

(B) $A=\begin{bmatrix}5 & -1 \\ 4 & 2\end{bmatrix}, \;\det(A)=5(2)-(-1)(4)=10+4=14$ $\;\;\Rightarrow \det(\text{adj}(A))=14$

(C) $A=\begin{bmatrix}6 & -1 \\ 2 & 1\end{bmatrix}, \;\det(A)=6(1)-(-1)(2)=6+2=8$ $\;\;\Rightarrow \det(\text{adj}(A))=8$

(D) $A=\begin{bmatrix}4 & 1 \\ 3 & 3\end{bmatrix}, \;\det(A)=4(3)-1(3)=12-3=9$ $\;\;\Rightarrow \det(\text{adj}(A))=9$