The modulus of the conjugate of $z=\frac{-2+i}{(1-2 i)^2}$ is

The modulus of the conjugate of $z=\frac{-2+i}{(1-2 i)^2}$ is
  1. $\frac{1}{5}$
  2. $\frac{1}{\sqrt{5}}$
  3. $\frac{1}{25}$
  4. $\sqrt{5}$

Solution

$\because z=\frac{-2+i}{(1-2 i)^2}$ $\begin{aligned} & z=\frac{i-2}{1-4-4 i}=\frac{i-2}{-3-4 i}=\frac{(2-i)(3-4 i)}{(3+4 i)(3-4 i)} \\ & z=\frac{2-11 i}{25} \text { Then, } \bar{z}=\frac{2+11 i}{25} \\ & |\bar{z}|=\left|\frac{2}{25}+\frac{11}{25} i\right|=\sqrt{\frac{4}{625}+\frac{121}{625}}=\sqrt{\frac{125}{625}}=\sqrt{\frac{1}{5}} \\ & \Rightarrow|\bar{z}|=\frac{1}{\sqrt{5}}\end{aligned}$

Asked in: AP EAMCET 2023 (17 May Shift 2)

Practice more Complex Number questions on Aicharya