CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2006

  • question_answer
    If \[2x=-1\,+\sqrt{3}\,i\], then the value of \[{{(1-{{x}^{2}}+x)}^{6}}-{{(1-x+{{x}^{2}})}^{6}}\] is equal to :

    A)  32                                         

    B)  -64

    C)  64                                         

    D)  0

    Correct Answer: D

    Solution :

    Given that \[2x=-1+\sqrt{3}i\]                 \[\Rightarrow \]               \[x=\frac{-1+\sqrt{3}i}{2}\]                                 \[=\omega \]                 \[\therefore \]  \[{{(1-{{x}^{2}}+x)}^{6}}-{{(1-x+{{x}^{2}})}^{6}}\]                 \[={{(1-{{\omega }^{2}}+\omega )}^{6}}-{{(1-\omega +{{\omega }^{2}})}^{6}}\]                 \[={{(-2{{\omega }^{2}})}^{6}}-{{(-2\omega )}^{6}}\]       ( \[\because \] \[1+\omega +{{\omega }^{2}}=0\])                 \[={{2}^{6}}\,{{\omega }^{12}}-{{2}^{6}}{{\omega }^{6}}\]                 \[={{2}^{6}}(1)-{{2}^{6}}(1)\]                      (\[\because \] \[{{\omega }^{3}}=1\])                 \[=0\]


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