Target Exam

CUET

Subject

-- Applied Mathematics - Section B2

Chapter

Algebra

Question:

Match List-I with List-II

List-I (Matrix A)

List-II (Determinant of adj A)

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

(I) 3

(B) $\begin{bmatrix}3&4\\3&6
\end{bmatrix}$

(II) 6

(C) $\begin{bmatrix}3&7\\-2&-4
\end{bmatrix}$

(III) 5

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

(IV) 2

Choose the correct answer from the options given below:

Options:

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

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

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

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

Correct Answer:

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

Explanation:

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

List-I (Matrix A)

List-II (Determinant of adj A)

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

(III) 5

(B) $\begin{bmatrix}3&4\\3&6
\end{bmatrix}$

(II) 6

(C) $\begin{bmatrix}3&7\\-2&-4
\end{bmatrix}$

(IV) 2

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

(I) 3

Formula: For a square matrix $A$ of order $n$, $\det(\text{adj } A) = (\det A)^{n-1}$

(A) $A = \begin{bmatrix}2 & 1 \\ -1 & 2\end{bmatrix}$, $\det A = 2*2 - (-1*1) = 4 + 1 = 5$, $n=2$

So, $\det(\text{adj } A) = (\det A)^{2-1} = 5^1 = 5 \Rightarrow$ matches (III)

(B) $A = \begin{bmatrix}3 & 4 \\ 3 & 6\end{bmatrix}$, $\det A = 3*6 - 3*4 = 18 - 12 = 6$, $n=2$

So, $\det(\text{adj } A) = 6^1 = 6 \Rightarrow$ matches (II)

(C) $A = \begin{bmatrix}3 & 7 \\ -2 & -4\end{bmatrix}$, $\det A = 3*(-4) - (-2*7) = -12 + 14 = 2$, $n=2$

So, $\det(\text{adj } A) = 2^1 = 2 \Rightarrow$ matches (IV)

(D) $A = \begin{bmatrix}4 & 3 \\ 3 & 3\end{bmatrix}$, $\det A = 4*3 - 3*3 = 12 - 9 = 3$, $n=2$

So, $\det(\text{adj } A) = 3^1 = 3 \Rightarrow$ matches (I)