RAJASTHAN ­ PET Rajasthan PET Solved Paper-2003

  • question_answer
    The value of the determinant\[\left| \begin{matrix}    a+ib & c+ib  \\    c-id & a-ib  \\ \end{matrix} \right|\]is

    A)  \[(a+b)(c-d)\]

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

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

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

    Correct Answer: C

    Solution :

     \[\left| \begin{matrix}    a+ib & c+id  \\    c-id & a-ib  \\ \end{matrix} \right|\] \[=(a-ib)(a-ib)-(c+id)(c-id)\] \[={{a}^{2}}-{{i}^{2}}{{b}^{2}}-({{c}^{2}}-{{i}^{2}}{{d}^{2}})\] \[={{a}^{2}}+{{b}^{2}}-{{c}^{2}}-{{d}^{2}}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner