A quadratic function is a function of the form <math>f(x)=ax^2+bx+c</math>, where a is nonzero.
In the case where the domain and codomain are R (the real numbers), the graph of such a function is a parabola.
... are made up of individuals and 16.7% have someone living alone who is 65 years of age or older. The average household size is 2.30 and the average family size is ...