What is the simplest way to proove

Thanks

Printable View

- July 18th 2010, 02:43 AMlosm1Sequence convergence proof
What is the simplest way to proove

Thanks - July 18th 2010, 02:57 AMProve It
This is the value of by definition.

Recall that is defined to be the base of the exponential function such that this function is its own derivative.

So if then we have

.

Clearly for this equation to hold true, that must mean

.

Now supposing we let , clearly as , so this means

.

Q.E.D. - July 18th 2010, 03:15 AMAlso sprach Zarathustra
Hello!

First of all e is just a sing for "special" number.

So, what you have is a infinite sequence of numbers.

Theorem:

If infinite sequence of numbers is bounded and monotonic, the our sequence is converges, in other words there is some number which is called the limit of infinite sequence of numbers.

From our theorem we need to prove two things:

1. Boundedness

2. Monotonicity.(?)

Prove: using Inequality of arithmetic and geometric means - Wikipedia, the free encyclopedia

1.

2.

- July 18th 2010, 05:46 AMchisigma
The correct setting of the problem is the proof that the sequence converges to a finite number that we call 'e' and is . All other results, like for example the well known relation used in the 'demostration', are derived from this fundamental preliminary result and not vice-versa...

Kind regards

- July 18th 2010, 06:01 AMProve It
Incorrect, is

**defined to be**the base of the exponential function such that this function is its own derivative.

Therefore the setting of from the definition and finding an expression for from the definition is perfectly acceptable.

But yes, you are correct in saying that when you get to the expression you need to prove exists and can be evaluated. - July 18th 2010, 06:35 AMchisigma
- July 18th 2010, 07:13 AMCaptainBlack
- July 18th 2010, 07:17 AMCaptainBlack
There are a number of ways of defining "e", since we regard what was to be proven as a definition it is obvious that this is to be proven from some other definition. Two that come to mind immediately are the base of natural logarithms and the solution of the IVP (differential equation).

Earlier posts in this thread have done what is required admirably.

Your post quoted above comes close to being insulting and will only lead to trouble.

CB - July 18th 2010, 07:21 AMProve It
Very well...

Assume that you can write as a polynomial .

Therefore

By setting we can see .

We also know that by definition, so differentiating both sides gives...

.

Let and we can see .

Differentiate both sides:

.

Let and we can see .

Differentiate both sides

.

Let and we can see .

It can be seen that if you were to continue this way you would get

.

By letting we find

.

But we have also shown that .

Therefore , proving that this limit exists, and by evaluating the sum to an acceptable number of terms, can be seen to be . - July 18th 2010, 07:43 PMchisigma
- July 18th 2010, 08:21 PMeumyang
Maybe I'm dense, but I thought the original question was to prove

.

The original poster wanted the simplest way to prove this, and he/she did not say anwhere that we could**not**use the definition. So I don't know why the insistence to prove it without this definition. - July 18th 2010, 09:12 PMProve It