Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Matrices

Question:

If $A=\begin{bmatrix}0&-3&2\\a&b&8\\-2&c&0\end{bmatrix}$ is skew-symmetric matrix, then

Options:

$b=0$ and $a+c=5$

$a=0$ and $b+c=5$

$b=0$ and $a+c=-5$

$c=0$ and $a+b=-5$

Correct Answer:

$b=0$ and $a+c=-5$

Explanation:

$A=\begin{bmatrix}0&-3&2\\a&b&8\\-2&c&0\end{bmatrix}$

$A^T=\begin{bmatrix}0&a&-2\\-3&b&c\\2&8&0\end{bmatrix}$

$(A=-A^T)$ skew symmetric

$⇒\begin{bmatrix}0&-3&2\\a&b&8\\-2&c&0\end{bmatrix}=\begin{bmatrix}0&-a&2\\3&-b&-c\\-2&-8&0\end{bmatrix}$

On comparison

$a=3$,  $b=-b⇒b=0$  $c=-8$

$a+c=-5\,\,b=0$