Target Exam

CUET

Subject

Section B1

Chapter

Matrices

Question:

If the matrix $A = \begin{bmatrix} 0 & a & -3 \\ 2 & 0 & -1 \\ b & 1 & 0 \end{bmatrix}$ is skew symmetric. Find the values of '$a$' and '$b$'.

Options:

$a=−2,b=3$

$a=2,b=−3$

$a=−2,b=−3$

$a=2,b=3$

Correct Answer:

$a=−2,b=3$

Explanation:

The correct answer is Option (1) → $a=−2,b=3$ ##

For a skew symmetric matrix $A' = -A$.

$A = \begin{bmatrix} 0 & a & -3 \\ 2 & 0 & -1 \\ b & 1 & 0 \end{bmatrix}$

$A' = \begin{bmatrix} 0 & 2 & b \\ a & 0 & 1 \\ -3 & -1 & 0 \end{bmatrix}, -A = \begin{bmatrix} 0 & -a & 3 \\ -2 & 0 & 1 \\ -b & -1 & 0 \end{bmatrix}$

$\begin{bmatrix} 0 & 2 & b \\ a & 0 & 1 \\ -3 & -1 & 0 \end{bmatrix} = \begin{bmatrix} 0 & -a & 3 \\ -2 & 0 & 1 \\ -b & -1 & 0 \end{bmatrix}$

On comparing we get,

$b = 3$ and $a = -2$.