CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2007

  • question_answer
    The value of \[\left| \begin{matrix}    x & p & q  \\    p & x & q  \\    p & q & x  \\ \end{matrix} \right|\] is

    A)  \[x(x-p)(x-q)\]

    B)  \[(x-p)(x-q)(x+p+q)\]

    C)  \[(p-q)(x-q)(x-p)\]

    D)  \[pq(x-p)(x-q)\]

    Correct Answer: B

    Solution :

    Given, \[\left| \begin{matrix}    x & p & q  \\    p & x & q  \\    p & q & x  \\ \end{matrix} \right|\] \[=x[{{x}^{2}}-{{q}^{2}}]-p[px-pq]+q[pq-px]\] \[={{x}^{3}}-x{{q}^{2}}-{{p}^{2}}x+{{p}^{2}}q+p{{q}^{2}}-pqx\] \[=x(x-q)(x+q)-{{p}^{2}}(x-q)-pq(x-q)\] \[=(x-q)[{{x}^{2}}+xq-{{p}^{2}}-pq]\] \[=(x-q)(x-p)(x+p+q)\]


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