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
    The value of the determinant  \[\left| \,\begin{matrix}    0 & {{b}^{3}}-{{a}^{3}} & {{c}^{3}}-{{a}^{3}}  \\    {{a}^{3}}-{{b}^{3}} & 0 & {{c}^{3}}-{{b}^{3}}  \\    {{a}^{3}}-{{c}^{3}} & {{b}^{3}}-{{c}^{3}} & 0  \\ \end{matrix}\, \right|\] is equal to  is equal to [J & K 2005]

    A) \[{{a}^{3}}+{{b}^{3}}+{{c}^{3}}\]

    B) \[{{a}^{3}}-{{b}^{3}}-{{c}^{3}}\]

    C) 0

    D) \[-{{a}^{3}}+{{b}^{3}}+{{c}^{3}}\]

    Correct Answer: C

    Solution :

    \[\left| \,\begin{matrix}    0 & {{b}^{3}}-{{a}^{3}} & {{c}^{3}}-{{a}^{3}}  \\    {{a}^{3}}-{{b}^{3}} & 0 & {{c}^{3}}-{{b}^{3}}  \\    {{a}^{3}}-{{c}^{3}} & {{b}^{3}}-{{c}^{3}} & 0  \\ \end{matrix}\, \right|\] \[({{b}^{3}}-{{a}^{3}})({{c}^{3}}-{{a}^{3}})\left| \,\begin{matrix}    0 & 1 & 1  \\    {{a}^{3}}-{{b}^{3}} & 1 & 1  \\    {{a}^{3}}-{{c}^{3}} & 1 & 1  \\ \end{matrix}\, \right|=0\] \[[{{C}_{2}}\to {{C}_{2}}-{{C}_{1}}\] and \[{{C}_{3}}\to {{C}_{3}}-{{C}_{1}}]\] and then taking out  common \[({{b}^{2}}-{{a}^{3}})\]from  IInd column and ( \[{{c}^{3}}-{{a}^{3}}\]) from  IIIrd column].


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