If a complex number $z$ statisfies the equation $x+\sqrt{2}|z+1|+i=0$, then $|z|$ is equal to :
If a complex number $z$ statisfies the equation $x+\sqrt{2}|z+1|+i=0$, then $|z|$ is equal to :
-
2
-
$\sqrt{3}$
-
$\sqrt{5}$
-
1
Solution
Given equation is
$
\begin{aligned}
& z+\sqrt{2}|z+1|+i=0 \\
& \text { put } z=x+i y \text { in the given equation. } \\
& (x+i y)+\sqrt{2}|x+i y+1|+i=0 \\
& \Rightarrow x+i y+\sqrt{2}\left[\sqrt{(x+1)^2+y^2}\right]+i=0
\end{aligned}
$
Now, equating real and imaginary part, we get
$
\begin{aligned}
& x+\sqrt{2} \sqrt{(x+1)^2+y^2}=0 \text { and } \\
& y+1=0 \Rightarrow y=-1 \\
& \Rightarrow x+\sqrt{2} \sqrt{(x+1)^2+(-1)^2}=0 \\
& \Rightarrow \sqrt{2} \sqrt{(x+1)^2+1}=-x \\
& \Rightarrow 2\left[(x+1)^2+1\right]=x^2 \\
& \Rightarrow x^2+4 x+4=0 \\
& \Rightarrow x=-2
\end{aligned}
$
Thus, $z=-2+i(-1) \Rightarrow|z|=\sqrt{5}$
Asked in: JEE Main 2013 (22 Apr Online)
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