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If the least and the largest real values of $$\alpha$$, for which the equation $$z + \alpha|z - 1| + 2i = 0$$ ($$z \in C$$ and $$i = \sqrt{-1}$$) has a solution, are $$p$$ and $$q$$ respectively; then $$4(p^2 + q^2)$$ is equal to ______.
Correct Answer: 10
Let
$$z=x+iy$$
Then,
$$x+iy+\alpha\sqrt{(x-1)^2+y^2}+2i=0$$
Equating real and imaginary parts,
$$x+\alpha\sqrt{(x-1)^2+y^2}=0 \quad\cdots(1)$$ and $$y+2=0$$
Hence,
$$y=-2$$
Substitute into (1):
$$x+\alpha\sqrt{(x-1)^2+4}=0$$
$$\alpha=-\frac{x}{\sqrt{(x-1)^2+4}}$$
Therefore,
$$\alpha^2=\frac{x^2}{(x-1)^2+4}$$
$$=\frac{x^2}{x^2-2x+5}$$
Let
$$f(x)=\frac{x^2}{x^2-2x+5}$$
Differentiate:
$$f'(x)=\frac{2x(x^2-2x+5)-x^2(2x-2)}{(x^2-2x+5)^2}$$
$$=\frac{2x(5-x)}{(x^2-2x+5)^2}$$
Hence critical points are $$x=0,\qquad x=5$$
Now,
$$f(0)=0$$
and
$$f(5)=\frac{25}{20}$$
$$=\frac54$$
Thus,
$$0\le\alpha^2\le\frac54$$
Hence,
$$-\frac{\sqrt5}{2}\le\alpha\le\frac{\sqrt5}{2}$$
Therefore,
$$p=-\frac{\sqrt5}{2},\qquad q=\frac{\sqrt5}{2}$$
Now,
$$4(p^2+q^2)=4\left(\frac54+\frac54\right)$$
$$=4\cdot\frac52$$
$$=10$$
Therefore, the required value is
$$\boxed{10}$$
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