Which of the following is a characteristic of a quadratic function?

A quadratic function is defined by an equation in the form of ( f(x) = ax^2 + bx + c ), where ( a ), ( b ), and ( c ) are constants, and ( a \neq 0 ). One of the most distinctive features of a quadratic function is its graph, which forms a parabola.

These parabolas can open upwards or downwards depending on the sign of the coefficient ( a ). If ( a ) is positive, the parabola opens upwards, and if ( a ) is negative, it opens downwards. This characteristic shape is essential to understanding how quadratic functions behave and can be used to analyze their properties, such as vertex, axis of symmetry, and intercepts.

Recognizing that the graph of a quadratic function is indeed a parabola helps to distinguish it from linear functions, which have graphs that are straight lines, as well as from other polynomial functions of different degrees.