1893 - Thomas Edison received two U.S. patents. The first was for a "Cut Out for Incandescent Electric Lamps" and another for a "Stop Device" (No. 491,992-3). Also No. 492,150 for "Process of Coating Conductors for Incandescent Lamps."
... If the discriminant is positive, then there are two different solutions x, both of which are real. (Geometrically, this means that the parabola intersects the x-axis in two ...