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.
... dB is the abbreviation for Decibel; see Bel
DB is a French automobile maker; see DB (car)
DB is the abbreviation for Deutsche Bahn, the major German railway company
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