JEE Main & Advanced AIEEE Paper (Held On 11 May 2011)

  • question_answer
    If the trivial solution is the only solution of the system of equations \[x-ky+z=0\] \[kx+3y-kz=0\] \[3x+y-z=0\] then the set of all values of k is :     AIEEE  Solved  Paper (Held On 11 May  2011)

    A)  R-{2,-3}        

    B)  R-{2}    

    C)  R-{-3}

    D)  {2,-3}

    Correct Answer: A

    Solution :

                    \[x-ky+z=0\] \[kx+3y-kz=0\] \[3x+y-z=0\]this equation will have non trivial solution if \[\left| \begin{matrix}    1 & -k & 1  \\    k & 3 & -k  \\    3 & 1 & -1  \\ \end{matrix} \right|=0\] \[1(-3+k)+k(-k+3k)+1(k-9)=0\] \[k-3+2{{k}^{2}}+k-9=0\] \[2{{k}^{2}}+2k-12=0\] \[{{k}^{2}}+k-6=0\] \[k=-3,k=2\]so the equation will have only trivial solution when\[k\in R-\{2,-3\}\]


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