Préfecture (capital): Périgueux[?].
Sous-préfectures: Bergerac[?], Nontron[?], Sarlat la Canéda[?].
See also: List of the communes of the Dordogne département
... quadratic formula expresses the explicit solution(s) x to the quadratic equation <math>ax^2+bx+c=0</math> in terms of the coefficients a, b and c, ...