Q. Let [$x\rbrack$ represent the greatest integer less than or equal to $x$, then the value of the determinant $\left| \begin{matrix} \lbrack e\rbrack & \lbrack\pi\rbrack & \left\lbrack \pi^{2} - 6 \right\rbrack \\ \lbrack\pi\rbrack & \left\lbrack \pi^{2} - 6 \right\rbrack & \lbrack e\rbrack \\ \left\lbrack \pi^{2} - 6 \right\rbrack & \lbrack e\rbrack & \lbrack\pi\rbrack \end{matrix} \right|$ is

A) $- 8$
B) 8
C) 10
D) None of these
Explanation

(a)
$\left| \begin{matrix}
\lbrack e\rbrack & \lbrack\pi\rbrack & \left\lbrack \pi^{2} - 6 \right\rbrack \\
\lbrack\pi\rbrack & \left\lbrack \pi^{2} - 6 \right\rbrack & \lbrack e\rbrack \\
\left\lbrack \pi^{2} - 6 \right\rbrack & \lbrack e\rbrack & \lbrack\pi\rbrack
\end{matrix} \right|$
$= \left| \begin{matrix}
2 & 3 & 3 \\
3 & 3 & 2 \\
3 & 2 & 3
\end{matrix} \right|$
$= 2(9 - 4) - 3(9 - 6) + 3(6 - 9)$
$= 10 - 9 - 9 = - 8$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.

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