Let $z$ be a complex number such that $|z|+z=3+i, i=\sqrt{-1}$, then $|z|$ is equal to

Let $z$ be a complex number such that $|z|+z=3+i, i=\sqrt{-1}$, then $|z|$ is equal to
  1. $\frac{5}{4}$
  2. $\frac{\sqrt{41}}{4}$
  3. $\frac{\sqrt{34}}{3}$
  4. $\frac{5}{3}$

Solution

$\begin{aligned} & |z|+z=3+i \\ & \Rightarrow \sqrt{x^2+y^2}+x+i y=3+i[\text { let } z=x+i y] \\ & \Rightarrow \sqrt{x^2+y^2}+x=3 \text { and } y=1 \\ & \Rightarrow \sqrt{x^2+1^2}+x=3 \\ & \Rightarrow x^2+1=(3-x)^2 \\ & \Rightarrow x=\frac{4}{3} \\ & \Rightarrow|z|=\sqrt{x^2+y^2}=\sqrt{\left(\frac{4}{3}\right)^2+1^2}=\frac{5}{3}\end{aligned}$

Asked in: MHT CET 2022 (06 Aug Shift 2)

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