Finding Limit: Hi, I've Got 2 Questions

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In summary, the conversation includes two questions about finding limits using L'Hopital's Rule. The first question involves an indeterminate form of 0/0, which is solved by using the derivative of e^(4x). The second question also involves an indeterminate form, but L'Hopital's Rule cannot be applied due to a vertical asymptote. The limit can be found by looking at the limit from both sides and plugging in values near x=2.
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kemmy
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Hi, I've got two questions here that I'm stuck on.
The first:

Homework Equations


Find the Limit as x->0 of [(e^4x)-1-4x]/x^2


The Attempt at a Solution


So far:
I got that the Limit as x->0 is indeterminate form 0/0 so I tried L'Hopital's:

to find the Limit as x->0 of [(e^4x)-4]/2x

but that gave me a Limit of -3/0 . So I think that means that there's no limit. But the book insists that the Limit is 8. and I have no idea how it got there.


the second question I'm confused about is

Homework Equations


Find the Limit as x->2 of (x+2)/[(x-2)^4] , and explain why L'Hopital's Rule does not apply.


The Attempt at a Solution


so
The Lim x->2 = 4/0 so it's not 0/0 indeterminate so L'Hopital's isn't applicable.

But after that I'm a bit stuck on how to get the Limit. I know that because x can't equal 0 in the denominator that x cannot equal 2. So there's a vertical asymptote there.
So...I know I can look at it from each side
The Limit as x->0- and as x->0+ .
So-
The Limit as x->0+=infinity
The Limit as x->0-=infinity.
is that right? and is their an easier way to find that then just plugging in numbers near x=2?

-Thanks, any help would be much appreciated!
 
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  • #2
The derivative of e^(4x) is 4e^(4x)... correct this and it should work out.
 

1. What is the concept of finding limit?

The concept of finding limit is a fundamental concept in calculus that deals with determining the behavior of a function as its input approaches a specific value. It is used to analyze the behavior of a function near a certain point and is essential in understanding the behavior of functions in various applications.

2. How do you find the limit of a function?

To find the limit of a function, you first need to determine the value that the input is approaching. Then, you can use various techniques such as substitution, factoring, or L'Hopital's rule to simplify the function and evaluate the limit. It is important to note that the limit may not always exist, and further analysis may be required to determine its value.

3. What is the difference between one-sided and two-sided limits?

A one-sided limit only considers the behavior of the function as the input approaches the specified value from one direction, either from the left or the right. On the other hand, a two-sided limit takes into account the behavior of the function from both directions. One-sided limits are used when the function is not defined on both sides of the specified value.

4. How is finding limit useful in real-life applications?

Finding limit is crucial in understanding the behavior of functions in real-life applications, such as in physics, engineering, and economics. It helps in analyzing the rate of change, optimization problems, and predicting future values. For example, in physics, finding limit is used to analyze the instantaneous velocity of an object at a specific point in time.

5. Are there any limitations to finding limit?

While finding limit is a powerful tool in calculus, it does have its limitations. One limitation is that it only considers the behavior of the function near a specific point and does not provide information about the entire function. Additionally, finding limit may not always be possible if the function is too complex or if the limit does not exist. In such cases, other techniques such as graphing or numerical methods may be used to analyze the function's behavior.

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