JEE Main & Advanced Mathematics Complex Numbers and Quadratic Equations Question Bank De Moivre's theorem and Roots of unity

  • question_answer
    If \[\omega =\frac{-1+\sqrt{3}i}{2}\]then \[{{(3+\omega +3{{\omega }^{2}})}^{4}}\]= [Karnataka CET 2004; Pb. CET 2000]

    A) 16

    B) -16

    C) 16 \[\omega \]

    D) 16\[{{\omega }^{2}}\]

    Correct Answer: C

    Solution :

    \[{{(3+\omega +3{{\omega }^{2}})}^{4}}=[{{(3+3{{\omega }^{2}}+\omega )}^{4}}]\] \[={{[\,3\,(1+{{\omega }^{2}})+\omega ]}^{4}}\]\[={{[3(-\omega )+\omega ]}^{4}}\] .


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