Consider the system of equations:
 $\lambda x+y+z=1$ ;
 $x+\lambda y+z=\lambda$ ;
$x+y+\lambda z={\lambda }^2.$  
Now, match the following lists:

	List – I		List – II
A	$\lambda =1$	P	Unique solution
B	$\lambda \ne 1$	Q	Infinite solution
C	$\lambda \ne 1,\lambda \ne -2$	R	No solution
D	$\lambda =-2$

 $\Delta ={(\lambda -1)}^2(\lambda +2)$
Now,   $\Delta =0if\lambda =1or\lambda =-2$ 
If $\lambda \ne 1,\lambda \ne -2,$ then the system has a unique solution.
If  $\lambda =1,$ the system becomes $x+y+z=1$ which has infinite solutions. If  $\lambda =-2,$ the system is inconsistent.