Math Is Fun Forum

tony123

Member

Registered: 2007-08-03

Posts: 229

lim

without l hopetal

find

when x-->0

mikau

Member

Registered: 2005-08-22

Posts: 1,504

Re: lim

are you allowed to assume lim sin(x)/x = 1? if so

lim (x - sin(x))/x^3 = lim (1/x^2) - lim(1/x^2)*lim sin(x)/x =  lim (1/x^2) -  lim (1/x^2)*1 =  lim (1/x^2 - 1/x^2) = lim(0) = 0.

i THINK thats right.

---

A logarithm is just a misspelled algorithm.

JaneFairfax

Member

Registered: 2007-02-23

Posts: 6,868

Re: lim

NO! THAT IS WRONG!

You can only use the rule

if both the limits

and

exist separately!!

In the case of

,

does not exist! So how the hell can you say

That is totally rubbish, man!!

The correct answer is

Last edited by JaneFairfax (2007-11-25 10:29:18)

luca-deltodesco

Member

Registered: 2006-05-05

Posts: 1,470

Re: lim

Apply L’Hôpital’s rule three times.

no need to get so angry also, he said he is not allowed to use l'hopitals rule

---

The Beginning Of All Things To End.
The End Of All Things To Come.

JaneFairfax

Member

Registered: 2007-02-23

Posts: 6,868

Re: lim

Sorry, I should have read Tony’s post more carefully.

Well, then I don’t know how to do it, if not by L’Hôpital’s.

Last edited by JaneFairfax (2007-11-25 10:32:57)

tony123

Member

Registered: 2007-08-03

Posts: 229

Re: lim

where

as

by Taylor's theorem.

Thus,

.

Last edited by tony123 (2007-11-30 10:43:51)

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: lim

Just to ask, do you know the answers to all your questions at the time you ask them?

The way you present your questions with little else said, and how you sometimes answer them yourself after a while suggests that instead of needing help, you're just giving us puzzles to do.

Not that that's a bad thing, but if that's the case then you should start your own exercises thread.

---

Why did the vector cross the road?
It wanted to be normal.

Krizalid

Member

Registered: 2007-03-09

Posts: 51

Re: lim

where

as

by Taylor's theorem.

Thus,

.

You stole this from a guy of another forum, what a shame.

You didn't even change any word.

Last edited by Krizalid (2007-12-01 01:49:23)

luca-deltodesco

Member

Registered: 2006-05-05

Posts: 1,470

Re: lim

Just to ask, do you know the answers to all your questions at the time you ask them?

perhaps not always, i sometimes start a thread with a question, but while waiting for any replies i continue to work on the problem myself, and if i have a revalation, ill update the thread with it.

Last edited by luca-deltodesco (2007-12-01 01:53:30)

---

The Beginning Of All Things To End.
The End Of All Things To Come.

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: lim

Sorry, I should have said that I was asking Tony, because it looks like he's posting questions that he already knows the answers to.

Your way is fine, because you genuinely want help at the time when you ask the question, and it just happens that the person who helps is yourself.

---

Why did the vector cross the road?
It wanted to be normal.

JaneFairfax

Member

Registered: 2007-02-23

Posts: 6,868

Re: lim

where

as

by Taylor's theorem.

Thus,

.

You stole this from a guy of another forum, what a shame.

You didn't even change any word.

Also,

as

is wrong! What he means is

, not

. For

.

Last edited by JaneFairfax (2007-12-01 06:15:39)

tony123

Member

Registered: 2007-08-03

Posts: 229

Re: lim

Welcome Youth
I have three other solutions to this problem
There is one other forums which he introduced this solution
To discuss this solution

And try to acquire other ideas

JaneFairfax im not a charlatan

Krizalid im not stole but i  have three other solutions to this problem

Thank you for all

JaneFairfax

Member

Registered: 2007-02-23

Posts: 6,868

Re: lim

Okay, I’m sorry. I take it back.