Let the system of linear equations

Question:

Let the system of linear equations

$4 x+\lambda y+2 z=0$

$2 x-y+z=0$

$\mu \mathrm{x}+2 \mathrm{y}+3 \mathrm{z}=0, \lambda, \mu \in \mathrm{R}$

has a non-trivial solution. Then which of the following is true?

  1. (1) $\mu=6, \lambda \in \mathrm{R}$

  2. (2) $\lambda=2, \mu \in \mathrm{R}$

  3. (3) $\lambda=3, \mu \in \mathrm{R}$

  4. (4) $\mu=-6, \lambda \in \mathrm{R}$


Correct Option: 1

Solution:

For non-trivial solution

$\left|\begin{array}{ccc}4 & \lambda & 2 \\ 2 & -1 & 1 \\ \mu & 2 & 3\end{array}\right|=0$

$\Rightarrow 2 \mu-6 \lambda+\lambda \mu=12$

when $\mu=6, \quad 12-6 \lambda+6 \lambda=12$

which is satisfied by all $\lambda$

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