If you are having trouble getting an equation into Pro/E just plot 10 points on the line and connect them with a spline.
You could also plot 10 points then overlay an approximate conic to get a smoother surface.
(Y = X² +6) has points at (0,6)(1,7)(-1,7)(2,10)(-2,10)... You remember it no matter how hard you tried to forget it... Keep it simple...
Best regards,
Frederick Burke