RAJASTHAN ­ PET Rajasthan PET Solved Paper-2003

  • question_answer
    \[\left| \begin{matrix}    1/a & {{a}^{2}} & bc  \\    1/b & {{b}^{2}} & ca  \\    1/c & {{c}^{2}} & ab  \\ \end{matrix} \right|\]is equal to

    A)  \[abc\]

    B)  0

    C)  1

    D)  \[a+b+c\]

    Correct Answer: B

    Solution :

     \[\left| \begin{matrix}    1/a & {{a}^{2}} & bc  \\    1/b & {{b}^{2}} & ca  \\    1/c & {{c}^{2}} & ab  \\ \end{matrix} \right|=\frac{1}{abc}\left| \begin{matrix}    1 & {{a}^{3}} & abc  \\    1 & {{b}^{3}} & abc  \\    1 & {{c}^{3}} & abc  \\ \end{matrix} \right|\] \[=\frac{abc}{abc}\left| \begin{matrix}    1 & {{a}^{3}} & 1  \\    1 & {{b}^{3}} & 1  \\    1 & {{c}^{3}} & 1  \\ \end{matrix} \right|\] \[=0\] [\[\because \]\[{{C}_{1}}\]and\[{{C}_{3}}\]are same]


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