A megahertz is one million (or 106) hertz.
See hertz, kilohertz (one thousand hertz), gigahertz[?] (109 hertz), terahertz[?] (1012 hertz), and petahertz[?] (1015 hertz).
... different cases: If the discriminant is zero, then there is a repeated solution x, and this solution is real. (Geometrically, this means that the parabola ...