Limit of a function
In calculus, a branch of mathematics, the limit of a function is the behavior of a certain function near a selected input value for that function. Limits are one of the main calculus topics, along with derivatives, integration, and differential equations.
Definition of the limit
changeThe definition of the limit is as follows:
- If the function approaches a number as approaches a number , then
The notation for the limit above is read as "The limit of as approaches is ", or alternatively, as (reads " tends to as tends to "[1]). Informally, this means that we can make as close to as possible—by making sufficiently close to from both sides (without making equal to ).[2]
Imagine we have a function such as . When , is undefined, because and division by zero is undefined. On the Cartesian coordinate system, the function would have a vertical asymptote at . In limit notation, this would be written as:
- The limit of as approaches is , which is denoted by
Right and left limits
changeConsider the function , we can get as close to in the -values as we want, so long as we do not make equal to . For instance, we could make x=.00000001 or -.00000001, but never 0. Therefore, we can get as close as we want to or depending on if we approach 0 from the right side or the left side.[3] The left limit is the limit the function tends to if we only approach the target x-value from the left, for instance in the case of when getting close to the 0 x-value from the left side, by using x-values that are smaller than 0, the limit would approach . In the same way, the right limit is the limit the function tends to if we only approach the target x-value from the right, for instance in the case of when getting close to the 0 x-value from the right side, by using x-values that are larger than 0, the limit would approach .
Related pages
change- Derivative (mathematics), a quantity defined as a limit of slopes
- Infinity
- Limit of a sequence
References
change- ↑ "List of Calculus and Analysis Symbols". Math Vault. 2020-05-11. Retrieved 2020-09-14.
- ↑ "Calculus I - The Limit". tutorial.math.lamar.edu. Retrieved 2020-09-14.
- ↑ "2.2: Limit of a Function and Limit Laws". Mathematics LibreTexts. 2018-04-11. Retrieved 2020-09-14.