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.
Answers. Best Answer: B. Cenozoic--recent life, age of mammals Mesozoic--middle life, age of reptiles, dinosaurs Paleozoic--ancient life, age of fishes, amphibians Archezoic (Archean)--an eon, not an era, life is microbes, algae, and later soft-bodied invertebrates. Source(s): jpm896 Â· 5 years ago. Thumbs up.