CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2007

  • question_answer
    \[\left| \begin{matrix}    \alpha  & -\beta  & 0  \\    0 & \alpha  & \beta   \\    \beta  & 0 & \alpha   \\ \end{matrix} \right|=0,\]then

    A)  \[\frac{\alpha }{\beta }\]is one of the cube roots of unity

    B) \[\alpha \]is one of the cube roots of unity

    C)  \[\beta \]is one of the cube roots of unity

    D)  \[\alpha \beta \]is one of the cube roots of unity

    E)  none of the above

    Correct Answer: A

    Solution :

    \[\left| \begin{matrix}    \alpha  & -\beta  & 0  \\    0 & \alpha  & \beta   \\    \beta  & 0 & \alpha   \\ \end{matrix} \right|=0\Rightarrow {{\alpha }^{2}}-{{\beta }^{3}}=0\] \[\Rightarrow \]\[{{\left( \frac{\alpha }{\beta } \right)}^{3}}=1\Rightarrow \frac{\alpha }{\beta }\]is one of the cube roots of unity


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