Let z=x+i y be a non-zero comp lex number such that

Question:

Let $z=x+i y$ be a non-zero comp lex number such that $z^{2}=i|z|^{2}$, where $i=\sqrt{-1}$, then $z$ lies on the:

  1. (1) line, $y=-x$

  2. (2) imaginaryaxis

  3. (3) line, $y=x$

  4. (4) real axis


Correct Option: , 3

Solution:

Let $z=x+i y$

$\because z^{2}=i|z|^{2}$

$\therefore x^{2}-y^{2}+2 i x y=i\left(x^{2}+y^{2}\right)$

$\Rightarrow x^{2}-y^{2}=0$ and $2 x y=x^{2}+y^{2}$

$\Rightarrow(x-y)(x+y)=0$ and $(x-y)^{2}=0$

$\Rightarrow x=y$

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