The value of

Question:

The value of $\mathrm{k} \in \mathbf{R}$, for which the following system of linear equations

$3 x-y+4 z=3$

$x+2 y-3 z=-2$

$6 x+5 y+k z=-3$

has infinitely many solutions, is :

  1. 3

  2. -5

  3. 5

  4. 3


Correct Option: , 2

Solution:

$\left|\begin{array}{ccc}3 & -1 & 4 \\ 1 & 2 & -3 \\ 6 & 5 & \mathrm{~K}\end{array}\right|=0$

$\Rightarrow 3(2 \mathrm{~K}+15)+\mathrm{K}+18-28=0$

$\Rightarrow 7 \mathrm{~K}+35=0 \Rightarrow \mathrm{K}=-5$

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