Specifically, there are "+sign" (tending to positive infinity) and "-sign" (tending to negative infinity) under lim. The specific calculation example is shown in the following figure:
Extended data:
1, the "limit" in mathematics means that a variable in a function gradually approaches a certain value A in the process of getting bigger (or smaller), and "it can never coincide with A" ("it can never be equal to A, but taking it equal to A' is enough to obtain a high-precision calculation result).
Limit is a description of "changing state". The value a that this variable always approaches is called the "limit value" (of course, it can also be expressed by other symbols).
2. Two important limitations:
( 1)?
2 or?
(where is irrational number, that is, the base of natural logarithm)
References:
Baidu Encyclopedia _ Restrictions