High School Calculus/Evaluating Limits
Evaluating Limits[edit | edit source]
What is a limit? A limit is a place on the graph that the function either does not touch or go past.
When evaluating a limit we may have to factor sometimes in order to get L. L is the point in which the function does not touch or go past.
Let's start off with a rather simple limit.
As you can see what we did was just plug 3 into the function to get L
This doesn't always work. This is easily shown in fractions.
I will show you two different ways to evaluate the limits. The first is by factoring and the second is by using L'Hopital's rule.
Evaluating Limits by Factoring[edit | edit source]
This is a fairly simply concept, not something easily done. It is especially hard if you have a hard time identifying how polynomials can be rewritten.
This gives us
Let's look at how is factored
By factoring we now get
Factoring the polynomial we find that it equals
Let's use the factored in the limit equation.
As you can see the (x-2) will cancel each other out. Leaving us with
This type evaluating limits will take some time, but with practice can be done quickly.
L'Hopital's Rule[edit | edit source]
This rule is my favorite way to solve limits with indeterminate form.
This way is a bit more advanced so I will cover it briefly, but I will show some examples and the idea behind it. This is probably something you will learn in Calculus II
When you have a limit that you have confirmed that is in indeterminate form you can use L'Hopital's Rule.
This is the rule
When , , , , , or use L'Hopital's rule. Which is
Now that we have identified that it is in an indeterminate form we use L'Hopital's rule
This is an extremely simplified form of how this rule is used. It is a really nice way to solve limit problems that give you indeterminate forms.