The general expression of a limit is as follows:

Where lim is the abbreviated way of writing limit, f (x) is the function under study and x → a reads "when x tends to the value a in the function", that is, when the variable x takes values very close to the value a and L is the result of the limit.

When speaking of the limit of a function, it is understood that it is the study of its behavior, at a specific point, but if we apply the analysis (separately) between the numbers less than the point and greater than it, we are talking about **lateral limits of a function**.

If the limit on the left and right of that point do not have the same value, we could say that the limit does not exist, therefore, the lateral limits are a way to verify its existence. In general, we can express this theorem as follows:

**Exercise 1**: Calculate the limit , being .

We apply the limit of the function in each case, let's start on the left:

The limit on the right will be:

We can see that the limits are different, therefore this** limit does not exist**.

**Exercise 2**: Determine the limit being .

We apply the limit of the function in each case; we start with the one on the left:

Now the limit on the right:

Like the **lateral limits are the same**, he **limit exists**.

**Exercise 3**: Determine if the following limit exists .

We will simplify the limit so as not to have an indeterminacy and then solve what is inside the root:

As we have already reduced the expression we apply the lateral limits, remembering the absolute value:

Now the limit on the right:

Since the lateral limits are not equal, this limit does not exist.