In the previous section we saw limits that were infinity and itâs now time to take a look at limits at infinity. By limits at infinity we mean one of the following two limits. In other words, we are going to be looking at what happens to a function if we let x get very large in either the positive or negative sense.
Testing the Device. Bellâs assistant, Thomas Watson, was in a nearby room in Bellâs workshop, waiting to see if Bellâs device would work. Bell spoke these famous words into his device: âMr. Watson, come here. Watson heard the words clearly and distinctly, and thus, the first working model of a telephone was born. Although there were other inventors working on similar designs, including one whose patent application was almost on the same day as Bell submitted his, Bellâs invention was the first actual working telephonic device.
The first cellular phone was invented and demonstrated in 1973 by Martin Cooper, an engineer and general manager for Motorola, who successfully developed a portable handset using cellular communications technology. Cooper made the first ever cellular phone call in April 1973 using the prototype Motorola Dyna-Tac.However, Cooper's first cellphone was the result of decades of research and development into mobile radio communications, and cellphones would not be widely used until 20 years after the Dyna-Tac.ooper made the first ever cellular phone call in April 1973 using the prototype Motorola Dyna-Tac. However, Cooper's first cellphone was the result of decades of research and development into mobile radio communications, and cellphones would not be widely used until 20 years after the Dyna-Tac.