CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2002

  • question_answer
    If the value of the determinant \[\left| \begin{matrix}    x+1 & 1 & 1  \\    2 & x+2 & 2  \\    3 & 3 & x+3  \\ \end{matrix} \right|\]is equal to zero, then\[x\]is:

    A)  0 and\[-6\]                        

    B)                         0 and 6

    C)                         6                                            

    D)                         \[-6\]

    E)                         \[0\]

    Correct Answer: A

    Solution :

    \[\left| \begin{matrix}    x+1 & 1 & 1  \\    2 & x+2 & 2  \\    3 & 3 & x+3  \\ \end{matrix} \right|=0\] \[\Rightarrow \]               \[\left| \begin{matrix}    x+6 & x+6 & x+6  \\    2 & x+2 & 2  \\    3 & 3 & x+3  \\ \end{matrix} \right|=0\]                                                 \[({{R}_{1}}\to {{R}_{1}}+{{R}_{2}}+{{R}_{3}})\] \[\Rightarrow \]               \[(x+6)\left| \begin{matrix}    1 & 0 & 0  \\    2 & x & 0  \\    3 & 0 & x  \\ \end{matrix} \right|=0\] \[\Rightarrow \]               \[(x+6){{x}^{2}}=0\]        \[\Rightarrow \]               \[x=0,-6\]


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