Q. $\left| \begin{matrix} \log e^{\ } & \log e^{2} & \log e^{3} \\ \log e^{2} & \log e^{3} & \log e^{4} \\ \log e^{3} & \log e^{4} & \log e^{5} \end{matrix} \right|$ is equal to

A) 0
B) 1
C) $4\log e$
D) $5\log e$
Explanation

(a)
$\left| \begin{matrix}
\log e^{\ } & \log e^{2} & \log e^{3} \\
\log e^{2} & \log e^{3} & \log e^{4} \\
\log e^{3} & \log e^{4} & \log e^{5}
\end{matrix} \right| = \left| \begin{matrix}
\log e^{\ } & {2log}e^{\ } & 3\log e^{\ } \\
{2log}e^{\ } & {3log}e^{\ } & {4log}e^{\ } \\
3\log e^{\ } & 4\log e^{\ } & {5log}e^{\ }
\end{matrix} \right|$
$= \left| \begin{array}{r}
1\ \ 2\ \ 3 \\
2\ \ 3\ \ 4 \\
3\ \ 4\ \ 5
\end{array} \right| = \left| \begin{array}{r}
1\ \ 1\ \ 1 \\
2\ \ 1\ \ 1 \\
3\ \ 1\ \ \ 1
\end{array} \right|$
(Using $C_{2} \rightarrow C_{2} - C_{1},\ C_{3} \rightarrow C_{3} - C_{2})$
$= 0\lbrack\therefore\$two columns are identical]

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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