If $z$ is a complex number with $|z| \geq 5$. Then the least value of $\left|z+\frac{2}{z}\right|$ is

If $z$ is a complex number with $|z| \geq 5$. Then the least value of $\left|z+\frac{2}{z}\right|$ is
  1. $\frac{24}{5}$
  2. $\frac{26}{5}$
  3. $\frac{23}{5}$
  4. $\frac{29}{5}$

Solution

We have given, $|z| \geq 5$ $ \begin{aligned} & \text { Now, }\left|z+\frac{2}{z}\right| \geq|z|-\left|\frac{2}{z}\right|=|| z\left|+\frac{2}{z}\right| \\ & =|| z\left|+2\left(\frac{-1}{|z|}\right)\right| \geq\left|5-\frac{2}{5}\right| \\ & \therefore\left|z+\frac{2}{z}\right| \geq \frac{23}{5} \end{aligned} $ Thus, the least value of $|\quad \underline{2}|$ is $\frac{23}{}$

Asked in: AP EAMCET 2017 (26 Apr Shift 1)

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