Early Styles (Musicians Active before 1930)
Early Country Blues
Early Urban Blues
Early Jazz Blues
Kansas City Blues
Later Styles
Post War Jazz Blues
Chicago Blues
Modern Blues (post 1950s)
Blues in conventional pop music
... being non-zero. These solutions are also called the roots of the equation. The formula reads <math> x=\frac{-b \pm \sqrt {b^2-4ac}}{2a} </math> The term ...