3 and 4 .Determinants and Matrices
easy

જો $\left| {\,\begin{array}{*{20}{c}}5&3&{ - 1}\\{ - 7}&x&{ - 3}\\9&6&{ - 2}\end{array}\,} \right| = 0$, તો  $ x$  મેળવો.

A

$3$

B

$5$

C

$7$

D

$9$

Solution

(d) We have $\Delta = \left| {\,\begin{array}{*{20}{c}}5&3&{ – 1}\\{ – 7}&x&{ – 3}\\9&6&{ – 2}\end{array}\,} \right|{\rm{ }} = {\rm{0}}$

$\therefore $ $ – 10x + 90 – 42 – 81 + 42 + 9x = 0\,\,{\rm{or}}\,{\rm{ }}x = 9$.

Standard 12
Mathematics

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