Pliz help me with calculus limits proof of (e)

In summary: In any event, I think the OP was looking for a method of evaluating the limit, so they couldn't just say "it's the definition".The least thing we can say is that everything is coherent ;)
  • #1
spektah
6
0

Homework Statement


Some on ehelp me prove this in detailed format using the knowledge of limits.



Homework Equations



lim(x-->infinity)(1+1/x)^x=e
 
Last edited:
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  • #2
Welcome to PF, spektah!

To receive help, you must either show your work or indicate on the part you are stuck on.

Remember, we help with your homework not do your homework.
 
  • #3
some body help.
 
  • #4
i just need a starting point i don't know where to begin from?
 
  • #5
according to my knowledge of calculus; that is one of the DEFINITIONS of e; you can't prove a definition.

But if you insert n = 1; you get 2.
And if you use the bionomial theorem, you can show that this limit is AT most 3.

So that 2< e < 3

So you can "only" show that this limit DOES exists.

http://en.wikipedia.org/wiki/Binomial_theorem
 
  • #6
thanx a lot.
 
  • #7
Help on partial derivatives...

Some one give me a starting point on this question
Givev all are partial derivatives.

Find (df/dx) and (df/dx) if f(x,y)=tan-1(y/x^(1/2))
 
  • #8
i think you meant df/dx and df/dy, and when finding partial derivatives, treat every other variable as a constant except the one you are differentiating with respect to.
 
  • #9
malawi_glenn said:
So you can "only" show that this limit DOES exists.

You can show that the limit is e, but I think you need something at least as strong as L'Hopital's Rule (after taking the natural logarithm of the expression and arranging the result into appropriate form) to prove it. I'm not aware of a nice shortcut.
 
  • #10
dynamicsolo said:
You can show that the limit is e, but I think you need something at least as strong as L'Hopital's Rule (after taking the natural logarithm of the expression and arranging the result into appropriate form) to prove it. I'm not aware of a nice shortcut.

According to my books, this is the definition of e, they (and me) could be wrong. I mean, the natural logarithm requires that you already have e and e^x right?
 
  • #11
malawi_glenn said:
According to my books, this is the definition of e, they (and me) could be wrong. I mean, the natural logarithm requires that you already have e and e^x right?

It is one definition of e, but it can be shown that this limit would have to have that value to be consistent with the definition of natural logarithm. I'd agree that there would be a certain circularity beyond that: you get as far as showing that this value must be the same as the base for natural logarithms.

(I had a look at what Wikipedia has on e, which jibes pretty much with the history I was familiar with. There are various ways to get e and, beyond that, you would just have checks for consistency.)

In any event, I think the OP was looking for a method of evaluating the limit, so they couldn't just say "it's the definition".
 
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  • #12
The least thing we can say is that everything is coherent ;)
 

1. What is a calculus limit proof?

A calculus limit proof is a mathematical method used to show the behavior of a function as it approaches a certain point or value. It involves evaluating the limit of the function and providing a rigorous mathematical argument to prove that the limit exists and has a specific value.

2. How do I approach a calculus limit proof?

The first step in approaching a calculus limit proof is to understand the definition of a limit and the properties of limits. Then, you can use algebraic manipulations, trigonometric identities, and other techniques to simplify the expression and evaluate the limit. Finally, you need to provide a logical and mathematical argument to prove the limit exists and has a specific value.

3. What is the difference between a limit and a derivative?

A limit and a derivative are both concepts in calculus, but they have different meanings and applications. A limit is used to describe the behavior of a function as it approaches a certain point, while a derivative is used to describe the instantaneous rate of change of a function at a specific point. In other words, a limit looks at the overall behavior of a function, while a derivative looks at the local behavior.

4. What is the significance of proving a calculus limit?

Proving a calculus limit is essential in understanding the behavior of a function and its properties. It allows us to make accurate predictions about the function and its values, which is crucial in many areas of mathematics, science, and engineering. Additionally, proving a limit is a fundamental skill in calculus and is often required in advanced courses.

5. Can you explain the epsilon-delta definition of a limit?

The epsilon-delta definition of a limit is a rigorous way to define the limit of a function. It states that for a given function f(x) and a point c, the limit of f(x) as x approaches c is L if for every positive number epsilon, there exists a positive number delta such that if the distance between x and c is less than delta, then the distance between f(x) and L is less than epsilon. In simpler terms, it means that as x gets closer and closer to c, f(x) gets closer and closer to L.

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