Target Exam

CUET

Subject

-- Mathematics - Section A

Chapter

Matrices

Question:

Let A be a matrix such that $A = \begin{bmatrix}1&2\\-2&3\end{bmatrix}$. Then which of the following are TRUE?

(A) A is non-singular matrix
(B) $A^T = A$
(C) A is not invertible matrix
(D) A is not skew-symmetric matrix

Choose the correct answer from the options given below: Choose the correct answer from the options given below:

Options:

(A) and (D) only

(B) and (C) only

(A) and (C) only

(C) and (D) only

Correct Answer:

(A) and (D) only

Explanation:

The correct answer is Option (1) → (A) and (D) only

Given:

$A = \begin{bmatrix} 1 & 2 \\ -2 & 3 \end{bmatrix}$

Determinant:

$|A| = (1)(3) - (2)(-2) = 3 + 4 = 7 \ne 0$

Hence, $A$ is non-singular ⇒ (A) is true, (C) is false.

Check symmetry:

$A^T = \begin{bmatrix} 1 & -2 \\ 2 & 3 \end{bmatrix}$

Since $A^T \ne A$, it is not symmetric.

Check skew-symmetry:

$-A = \begin{bmatrix} -1 & -2 \\ 2 & -3 \end{bmatrix}$

$A^T \ne -A$, hence it is not skew-symmetric.

Therefore, correct statements:

(A) A is non-singular matrix

(D) A is not skew-symmetric matrix