JEE Main & Advanced JEE Main Paper (Held on 7 May 2012)

  • question_answer
    If the system of equations \[x+y+z=6\] \[x+2y+3z=10\] \[x+2y+\lambda z=0\] has a unique solution, then \[\lambda \] is not equal to   JEE Main Online Paper (Held On 07 May 2012)

    A) 1                                             

    B)                        0

    C)                        2                                             

    D)                        3

    Correct Answer: D

    Solution :

                    Given system of equations is \[x+y+z=6\] \[x+2y+3z=10\] \[x+2y+\lambda z=0\]It has unique solution. \[\therefore \]\[\left| \begin{matrix}    1 & 1 &1  \\    1 & 2 &3  \\    1 & 2 & \lambda   \\ \end{matrix} \right|\ne 0\] \[\Rightarrow \]\[1(2\lambda -6)-1(\lambda -3)+1(2-2)\ne 0\] \[\Rightarrow \]\[2\lambda -6-\lambda +3\ne 0\Rightarrow \lambda =3\ne 0\Rightarrow \lambda \ne 3\]


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