Préfecture (capital): Niort[?]
Sous-préfectures: Bressuire[?] and Parthenay[?].
See also: Communes of the Deux-Sèvres département
... for details. Derivation The quadratic formula is derived by the method of completing the square[?]. <math>ax^2+bx+c=0</math> Dividing o ...