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."
... the x-axis in a single point.)
If the discriminant is positive, then there are two different solutions x, both of which are real. (Geometrically, this means that the ...