Let \( S = \left\{ z = x + iy : \dfrac{2z - 3i}{4z + 2i} \text{ is a real numbers} \right\} \). Then which of the following is NOT correct?
\( (x, y) = \left( 0, -\dfrac{1}{2} \right) \)
\( y \in \left( -\infty, -\dfrac{1}{2} \right) \cup \left( -\dfrac{1}{2}, \infty \right) \)
\( y + x^2 + y^2 \neq \dfrac{1}{4} \)
\( x = 0 \)