CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2010

  • question_answer
    If \[x+iy={{(-1+i\sqrt{3})}^{2010}},\] then x is

    A) \[-{{2}^{2010}}\]                              

    B) \[{{2}^{2010}}\]

    C) \[1\]                                     

    D) \[-1\]

    Correct Answer: B

    Solution :

     \[x+iy={{(-1+i\sqrt{3})}^{2010}}\] \[\Rightarrow \]               \[x+iy={{(2)}^{2010}}{{\left( \frac{-1+i\sqrt{3}}{2} \right)}^{2010}}\]                                 \[\left( \because \,\,\,\omega =\frac{-1+i\sqrt{3}}{2} \right)\] \[\Rightarrow \]               \[(x+iy)={{(2)}^{2010}}{{\omega }^{2010}}\] \[\Rightarrow \]               \[(x+iy)={{(2)}^{2010}}{{({{\omega }^{3}})}^{670}}\]                        \[(\because \,\,{{\omega }^{3}}=1)\] \[\Rightarrow \]               \[(x+iy)={{(2)}^{2010}}{{(1)}^{670}}={{2}^{2010}}+i.0\] On comparing real part \[\Rightarrow \]               \[x={{2}^{2010}}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner