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
    \[\left| \,\begin{matrix}    1 & 1 & 1  \\    1 & {{\omega }^{2}} & \omega   \\    1 & \omega  & {{\omega }^{2}}  \\ \end{matrix}\, \right|=\] [RPET 2002]

    A) \[3\sqrt{3}i\]

    B) \[-3\sqrt{3}i\]

    C) \[i\sqrt{3}\]

    D) 3

    Correct Answer: A

    Solution :

      \[\left| \,\begin{matrix}    1 & 1 & 1  \\    1 & {{\omega }^{2}} & \omega   \\    1 & \omega  & {{\omega }^{2}}  \\ \end{matrix}\, \right|\,=3(\omega -{{\omega }^{2}})\] \[=3\,\left[ \frac{-1+\sqrt{3}i}{2}-\frac{-1-\sqrt{3}i}{2} \right]=3\sqrt{3}\,i\].


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