J & K CET Engineering J and K - CET Engineering Solved Paper-2012

  • question_answer
    \[{{i}^{i}}\] (when \[i=\sqrt{-1}\]) is                        

    A)  a purely real number                 

    B)  a purely complex number               

    C)  a complex number whose real part is always a negative real number

    D)  a complex number whose real part is always a positive integer                  

    Correct Answer: A

    Solution :

    Let \[(a+ib)={{i}^{i}}\] Taking log on both sides, we get \[\log (a+ib)=i\,\log \,i\] \[\Rightarrow \] \[\log (a+ib)=i\left( i\frac{\pi }{2} \right)\] \[\Rightarrow \] \[\log (a+ib)=-\frac{\pi }{2}\] \[\Rightarrow \] \[(a+ib)={{e}^{-\pi /2}}\] Hence, \[{{i}^{i}}\] is purely real number.


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