J & K CET Engineering J and K - CET Engineering Solved Paper-2006

  • question_answer
    If \[A=\left[ \begin{matrix}    0 & -3 & -4/3  \\    3 & 0 & -1/4  \\    4/3 & 1/4 & 0  \\ \end{matrix} \right],\] then det \[(A+{{A}^{T}})\] is equal to                                 

    A)  \[0\]              

    B)  \[1\]

    C)  \[2\]             

    D)  \[3\]

    Correct Answer: A

    Solution :

    Given,    \[A=\left[ \begin{matrix}    0 & -3 & -4/3  \\    3 & 0 & -1/4  \\    4/3 & 1/4 & 0  \\ \end{matrix} \right]\] \[\therefore \] \[{{A}^{T}}=\left[ \begin{matrix}    0 & 3 & 4/3  \\    -3 & 0 & 1/4  \\    -4/3 & -1/4 & 0  \\ \end{matrix} \right]\] Now,   \[A+{{A}^{T}}=\left[ \begin{matrix}    0 & 0 & 0  \\    0 & 0 & 0  \\    0 & 0 & 0  \\ \end{matrix} \right]\] \[\therefore \] \[\det \,(A+{{A}^{T}})=0\]


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