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3 and 4 .Determinants and Matrices
medium
The value of $k$ for which the set of equations $x + ky + 3z = 0,$ $3x + ky - 2z = 0,$ $2x + 3y - 4z = 0$ has a non trivial solution over the set of rationals is
A
$15$
B
$31/2$
C
$16$
D
$33/2$
Solution
(d) Given set of equations will have a non trivial solution if the determinant of coefficient of $x, y, z $ is zero
i.e., $\left| {\,\begin{array}{*{20}{c}}1&k&3\\3&k&{ – 2}\\2&3&{ – 4}\end{array}\,} \right| = \,0\, $
$\Rightarrow 2k – 33 = 0$ or $k = \frac{{33}}{2}$.
Standard 12
Mathematics