JEE Main & Advanced Mathematics Determinants & Matrices Question Bank Expansion of determinants, Solution of equation in the form of determinants and properties of determinants

  • question_answer
    \[\left| \,\begin{matrix}    1 & a & b  \\    -a & 1 & c  \\    -b & -c & 1  \\ \end{matrix}\, \right|=\] [MP PET 1991]

    A) \[1+{{a}^{2}}+{{b}^{2}}+{{c}^{2}}\]

    B) \[1-{{a}^{2}}+{{b}^{2}}+{{c}^{2}}\]

    C) \[1+{{a}^{2}}+{{b}^{2}}-{{c}^{2}}\]

    D) \[1+{{a}^{2}}-{{b}^{2}}+{{c}^{2}}\]

    Correct Answer: A

    Solution :

    \[\left| \,\begin{matrix}    1 & a & b  \\    -a & 1 & c  \\    -b & -c & 1  \\ \end{matrix}\, \right|=1\,(1+{{c}^{2}})-a(-a+bc)+b(ac+b)\]               = \[1+{{a}^{2}}+{{b}^{2}}+{{c}^{2}}\].


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