The values of

Question:

The values of $\lambda$ and $\mu$ for which the system of linear equations

$x+y+z=2$

$x+2 y+3 z=5$

$x+3 y+\lambda z=\mu$

has infinitely many solutions are, respectively:

 

  1. (1) 6 and 8

  2. (2) 5 and 7

  3. (3) 5 and 8

  4. (4) 4 and 9


Correct Option: , 3

Solution:

$D=\left|\begin{array}{lll}1 & 1 & 1 \\ 1 & 2 & 3 \\ 1 & 3 & \lambda\end{array}\right|=0 \Rightarrow \lambda=5$

$D_{x}=\left|\begin{array}{lll}2 & 1 & 1 \\ 5 & 2 & 3 \\ \mu & 3 & 5\end{array}\right|=0 \Rightarrow \mu=8$

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