description of subset of parabolas that are non-quadratic functions ?

[shahar]

The graphs of quadratic function is subset of the set of parabolas.

What the description (or equation) of the other subsets of the set of parabolas (that are not quadratic function)? [The complementary sets...)?

 

[Dr.Peterson]

The graphs of quadratic function is subset of the set of parabolas.

What the description (or equation) of the other subsets of the set of parabolas (that are not quadratic function)? [The complementary sets...)?

Any parabola whose axis is parallel to the y-axis is the graph of a quadratic function.

But a parabola can have its axis in any direction. The complement of the set of graphs of quadratic functions is the set of parabolas whose axes are not parallel to the y-axis.

 

[stapel]

The graphs of quadratic function is subset of the set of parabolas.

What the description (or equation) of the other subsets of the set of parabolas (that are not quadratic function)? [The complementary sets...)?

To expand on what has already been said, I think the specification here of the subset is that there are parabolas (that is, things which obey the classical geometric definition of that shape of curve) which are not functions. That is, their equations will be "quadratic" (that is, having squared variables), but that quadratic cannot be solved for "y=", and the graphs of the parabolas will not obey the Vertical Line Test (because of being "tipped over" to a sufficient degree).