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.
... the abbreviation for Deutsche Bahn, the major German railway company
DB is the abbreviation of Dominion Breweries[?], a major beer brewing company of New Zealand.
This ...