JEE Main & Advanced Mathematics Complex Numbers and Quadratic Equations Question Bank Conjugate, Modulus and Argument of complex number

  • question_answer
    The maximum value of \[|z|\] where z satisfies the condition \[\left| z+\frac{2}{z} \right|=2\] is

    A) \[\sqrt{3}-1\]

    B) \[\sqrt{3}+1\]

    C) \[\sqrt{3}\]

    D) \[\sqrt{2}+\sqrt{3}\]

    Correct Answer: B

    Solution :

    \[\left| z+\frac{2}{z} \right|=2\Rightarrow |z|-\frac{2}{|z|}\le 2\]Þ\[|z{{|}^{2}}-2|z|-2\le 0\] \[|z|\le \frac{2\pm \sqrt{4+8}}{2}\le 1\pm \sqrt{3}\]. Hence max. value of  \[|z|\]is \[1+\sqrt{3}\]


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