see also: Elf[?] (1971-1976), Rainbow (1974-1979), Black Sabbath (1979-1983; returns 1991) and Dio (1982-present)
Discography:
With Rainbow
With Black Sabbath
With Dio
... discriminant of the quadratic equation, because it discriminates between three qualitatively different cases: If the discriminant is zero, then there is a repeated ...