Question

$\begin{vmatrix}13&16&19\\ 14&17&20\\ 15&18&21\end{vmatrix}$ is equal to:

• A. 57
• B. -39
• C. 96
• D. 0

Answer 1

Answer: (D)

Let $A=\begin{vmatrix}13&16&19\\ 14&17&20\\ 15&18&21\end{vmatrix}$
Operate $R_{2}\rightarrow R_{2}-R_{1}, R_{3}\rightarrow R_{3}-R_{2}$
Then $A=\begin{vmatrix}13&16&19\\ 1&1&1\\ 1&1&1\end{vmatrix}=0$
$(\because $ entry of two rows are same)