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Sum of squares of modulus of all the complex numbers $$z$$ satisfying $$\bar{z} = iz^2 + z^2 - z$$ is equal to
Correct Answer: 2
Given,
$$\bar z=iz^2+z^2-z$$
Let
$$z=x+iy$$
Then,
$$\bar z=x-iy$$
Substituting,
$$x-iy=(1+i)(x+iy)^2-(x+iy)$$
Comparing real and imaginary parts,
$$2x=x^2-y^2-2xy$$
and
$$x^2-y^2+2xy=0$$
Using the second equation in the first,
$$2x=-4xy$$
$$x(1+2y)=0$$
Hence,
$$x=0\quad \text{or}\quad y=-\frac12$$
Case 1:
$$x=0$$
Then from
$$x^2-y^2+2xy=0$$
we get
$$y=0$$
Hence,
$$z=0$$
Case 2:
$$y=-\frac12$$
Substituting in
$$x^2-y^2+2xy=0$$
$$x^2-\frac14-x=0$$
$$4x^2-4x-1=0$$
$$2x-1=\pm\sqrt2$$
$$x=\frac{1\pm\sqrt2}{2}$$
Thus,
$$z=\frac{1+\sqrt2}{2}-\frac{i}{2}$$
or
$$z=\frac{1-\sqrt2}{2}-\frac{i}{2}$$
Now,
$$|0|^2=0$$
$$\left|\frac{1+\sqrt2}{2}-\frac{i}{2}\right|^2 = \frac{(1+\sqrt2)^2+1}{4}$$
$$\left|\frac{1-\sqrt2}{2}-\frac{i}{2}\right|^2 = \frac{(1-\sqrt2)^2+1}{4}$$
Therefore,
$$0+\frac{(1+\sqrt2)^2+1}{4}+\frac{(1-\sqrt2)^2+1}{4}=2$$
Hence,
$$\boxed{2}$$
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