A limit is the behavior of a function as its inputs approach arbitrarily close to a given value.
Limits are written in the following form:
The expression above states that when approaches arbitrarily close to , the function becomes arbitrarily close to the value , which is called the limit.
We can examine the limit of a simple continuous function, .
We want to examine the limit of x= 0 for this function. Since this graph is a simple unbroken line, we realize that
Indeed for this function, . But this is a special case, in the majority of limits cannot be solved in this manner.
For a very different example; given
(as pictured below)
The limit of because x approaches 0 is 0 (just as in ), but ; is not continuous at (as shown on the right).
In other cases a limit can fail to exist, as approaching the limit from different sides produces conflicting values.
Here we look at one such case:
(as pictured above)
Rigorous Definition of Limit
This definition is more appropriate for 2nd year calculus students and higher.
For More Information
Even more mathematical description -
Properties of Limits
Ideas for the Future
- an interactive diagram in which changing the size of epsilon shows a corresponding delta, or something.