"Limit" is the basic concept of calculus, a branch of mathematics. The "limit" in a broad sense is "infinitely close and never reached". In mathematics, "limit" 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 a value equal to A' is enough to obtain a high-precision calculation result), and the change of this variable is artificially defined as" forever approaching ".

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).

Extended data

The method of finding the limit:

1, in the fraction, the numerator and denominator are divided by the highest degree, and infinity is calculated as infinitesimal, and infinitesimal is directly substituted into 0;

2. When the infinite root is subtracted, the molecule is physical and chemical, and then the method in (1) is used;

3. Apply two special restrictions;

4. Apply L'H?pital's law, but the application condition of L'H?pital's law is that it is transformed into infinity ratio or infinitesimal ratio, and the denominator of the numerator must also be a continuously derivable function. It is not invincible and cannot replace all other methods. The first floor is exaggerated.

5. The expansion is based on McLaughlin series, but it is generally misinterpreted as Taylor expansion in China.

6. Equal-order infinitesimal substitution, which is very popular in China, is relatively calm abroad. Because it is not a teaching method worth popularizing; Second, you often make mistakes, so be especially careful.

7. Extrusion method. This is not a universal method, because it is impossible to get the same result after zooming in and out.

8, under special circumstances, into the integral calculation.

9. Other methods that are extremely special and cannot be widely used.