Final answer:
The equation represents an ellipse in the x-y plane.
Step-by-step explanation:
The equation y² + 40 = x represents an ellipse in the x-y plane. An ellipse is a closed curve such that the sum of the distances from a point on the curve to the two foci is constant. In the given equation, there is a positive constant value of 40 added to the variable x, indicating an ellipse.