The Brussels Capital region has the following 19 municipalities:
(Note: seven municipalities have only one official name; the other twelve officially have both a Dutch and a French name. Both names are included in this list.)
... we get
<math>x=\frac{-b}{2a}\pm\frac{\sqrt{b^2-4ac}}{2a}=\frac{-b\pm\sqrt{b^2-4ac}}{2a}.</math>
Generalizations
The formula and its proof remain ...