The Battle of Rosbach was a part of the Seven Years War. It was fought on November 5, 1757 and resulted the victory of King Frederick II of Prussia over the French and Bavarians under General Soubise[?] and General Saxe-Hildburghausen. The victory blocked the French invasion of Germany.
... as "either of those element(s) of the field whose square equals b2 - 4ac". In some fields, some elements have no square roots and some have two; only zero has just one ...