Which of the following is not an example of a quadratic inequality?

A quadratic equation is a polynomial equation in which a single variable appears in a 2nd-degree term, and all other terms are 1st degree or less. A quadratic inequality is a quadratic equation in which the equal sign has been replaced by an inequality symbol.

The relation of selection A would not be a quadratic equation if the relation symbol were an equal sign, hence it is not a quadratic inequality. The best choice is

... A. y ≤ y² + x²