[tex]\it \dfrac{x}{2}=y^2 \Longrightarrow x = 2y^2\ \ \ \ (1)
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\dfrac{x}{4} = 4y \Longrightarrow x = 16y\ \ \ \ (2)
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(1),\ (2) \Longrightarrow 2y^2=16y|_{:2} \Longrightarrow y^2 = 8y \Longrightarrow y^2-8y=0 \Longrightarrow
[/tex]
[tex]\it \Longrightarrow y(y-8) = 0 \Longrightarrow \begin{cases} \it y_1 = 0 \ \ \ \ (3)
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\it y-8=0 \Longrightarrow y_2 = 8\ \ \ \ (4) \end{cases}[/tex]
[tex]\it (2),\ (3) \Longrightarrow x = 0
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(2), (4) \Longrightarrow x = 128
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Deci,\ (x,\ y)\in \{(0,\ 0),\ (128,\ 8)\}[/tex]
