RAJASTHAN ­ PET Rajasthan PET Solved Paper-2002

  • question_answer
    If\[z=\frac{\sqrt{3}+i}{2},\]then\[{{z}^{69}}\]is equal to

    A)  \[1\]             

    B)  2

    C)  \[-2\]            

    D)  \[-1\]

    Correct Answer: C

    Solution :

     \[z=\frac{\sqrt{3}+i}{2}\] \[=i\left[ \frac{\sqrt{3}}{2i}+\frac{1}{2} \right]\] \[=i\left[ \frac{1}{2}-\frac{i\sqrt{3}}{2} \right]\] \[=-i\left( -\frac{1}{2}+\frac{i\sqrt{3}}{2} \right)\] \[=-i\omega \] \[{{z}^{69}}={{(-i\omega )}^{69}}\] \[={{(-i)}^{69}}.{{\omega }^{69}}\] \[={{(-1)}^{69}}.i{{({{\omega }^{3}})}^{23}}\] \[={{(-1)}^{23}}=-i\]


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