The St. Louis blues is a type of blues music. It is usually more piano-based than other forms of the blues, and is closely related to the jump blues, ragtime and piano blues. Typically, a small number of singers, a pianist and a few other instruments (used primarily for rhythm) make up a band.
... quadratic equation touches the x-axis in a single point.)
If the discriminant is positive, then there are two different solutions x, both of which are real. ...