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
    \[\left| \,\begin{matrix}    {{a}_{1}} & m{{a}_{1}} & {{b}_{1}}  \\    {{a}_{2}} & m{{a}_{2}} & {{b}_{2}}  \\    {{a}_{3}} & m{{a}_{3}} & {{b}_{3}}  \\ \end{matrix}\, \right|=\] [RPET 1989]

    A) 0

    B) \[m{{a}_{1}}{{a}_{2}}{{a}_{3}}\]

    C) \[m{{a}_{1}}{{a}_{2}}{{b}_{3}}\]

    D) \[m{{b}_{1}}{{a}_{2}}{{a}_{3}}\]

    Correct Answer: A

    Solution :

    \[\left| \,\begin{matrix}    {{a}_{1}} & m{{a}_{1}} & {{b}_{1}}  \\    {{a}_{2}} & m{{a}_{2}} & {{b}_{2}}  \\    {{a}_{3}} & m{{a}_{3}} & {{b}_{3}}  \\ \end{matrix}\, \right|=m\,\left| \,\begin{matrix}    {{a}_{1}} & {{a}_{1}} & {{b}_{1}}  \\    {{a}_{2}} & {{a}_{2}} & {{b}_{2}}  \\    {{a}_{3}} & {{a}_{3}} & {{b}_{3}}  \\ \end{matrix}\, \right|=0\],  \[\{\therefore {{C}_{1}}\equiv {{C}_{2}}\}\].


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