A parabola with a vertex at (0,0) has a focus along the negative part of the x-axis.

A parabola with its vertex at (0, 0) and focus on the x-axis opens horizontally, so its equation has the form y² = 4px. A focus on the negative x-axis means p is negative, making the coefficient of x negative. Among the choices, y² = –2x matches; x² equations describe parabolas that open vertically.

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