We can't use both. The answer is to use the one with the smaller absolute value: With this definition of. A slightly different formal definition of the limit is used when x goes to +/- infinity, since we really cannot subtract x from infinity or vice versa-remember, infinity is a concept, not a number. Formally, the expression. Means that.
During the long interval of the Precambrian Era (which includes approximately 90% of geologic time and includes three Eons: the Hadean, the Archean and the Proterozoic) the only inhabitants of the Earth were simple microscopic organisms, many of them comparable in size and complexity to modern-day bacteria.
During the Triassic period, Eozostrodon was the first mammals. Some scientists believe that the mammals were evolved from the extinct mammal-like reptiles like Therapsids. There were detected the first-turtle too, called as Proganochelvs. Other creatures that lived in Triassic Period are Turtles, Salamanders, Lizards, and Pterosaurs. The Ancestor of Archaeopteryx was appeared, named as Pseudosuchia. Aetosaurs like Desmatosuchus also lived in the same time. Under the sea, the first marine dinosaurs, Ichtyosaurs appeared. The Triassicâs climate was generally dry and hot.