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
... We get <math>\left(x+\frac{b}{2a}\right)^2=\frac{-4ac+b^2}{4a^2}=\frac{b^2-4ac}{4a^2}.</math> Taking square roots of bo ...