Target Exam

CUET

Subject

-- Mathematics - Section A

Chapter

Matrices

Question:

If $\begin{bmatrix} x-2 & 3 & -2 \\ y & 0 & -4 \\ 2 & z & 0 \end{bmatrix}$ is a skew symmetric matrix, then the value of \( x + y + z \) is

Options:

9

-1

7

3

Correct Answer:

3

Explanation:

The correct answer is Option (4) → 3

For a skew–symmetric matrix, the condition is that the transpose of the matrix equals the negative of the matrix, that is A^T=−A. This means two important things:

  1. All diagonal elements must be zero.

  2. Elements symmetric about the main diagonal are negatives of each other.

Given matrix:

$\begin{bmatrix} x-2 & 3 & -2 \\ y & 0 & -4 \\ 2 & z & 0 \end{bmatrix}$ is a skew symmetric matrix, then the value of \( x + y + z \)

First, diagonal elements must be zero. So x−2=0 ⇒ x=2

Next, compare symmetric positions:

 

  • Element (1,2) = 3, so element (2,1) = y=−3
  • Element (1,3) = -2, so element (3,1) must be 2, which already matches.

  • Element (2,3) = -4, so element (3,2) = z = 4

    Now find x+y+z = 2+(−3)+4 =3