Semyon Alekseyevich Lavochkin (1900 - June 9, 1960) was a Sovietaircraft designer, born in Smolensk, Russia, responsible for several important fighter aircraft in World War II. His fortunes faded after the war, his aircraft consistently placing second in competitions with other design bureaux, notably that of Artem Ivanovich Mikoyan, and upon his death his design bureau was closed.
... the formula should be understood as "either of those element(s) of the field whose square equals b2 - 4ac". In some fields, some elements have no square roots and ...