1
   

L'hospital's Rules tricky proofs need help

 
 
Reply Wed 10 Nov, 2004 12:39 am
Edit [Moderator]: Moved from General to Science & Mathematics.

I am introducing myself, good lookin female -- double major for BS in physics and BA in technical theatre with math minor -- freaking out over calculus ineptitude and jealous of the only 2 people in my class who actually "get it". check out my webpage if you want to get to know me Edit (Moderator): Link removed I Just need some reasurance or correction for two problems that use L'hospital's Rule.

1. The lim as x->infinity of (1 + a/x) to the power bx.

I managed to get lim of (a(bsquared))/ (1 +a/x) = + infinity with some implicit differentiation and I could be totally wrong but at some point I need to get the right answer into the form e but I am having a brain cramp or something and I can't find it anywhere I was thinking the answer was e to the x power but I have a feeling it can't be that easy and there are more terms floating around that need to be included in the e form.


2. So when proving this: The lim as x-> infinity for (lnx)/(x to the power p) = 0

It is because when we use L'hospital's rule we get eventually lim (1/x)/(P!)
Right? but where do I go from here to get to prove that for any p>0 that the logarithmic function approaches infinity more slowly than any power of x. Do I need to do L'hospital's again and if I do what is the logarithmic form I'm supposed to sub in to get back into a form where the lim of the function is determinate one and is zero?
  • Topic Stats
  • Top Replies
  • Link to this Topic
Type: Discussion • Score: 1 • Views: 1,085 • Replies: 7
No top replies

 
Don1
 
  1  
Reply Wed 10 Nov, 2004 02:47 am
You would probably have more luck with this butterfryby if you put it in the mathematics section. Welcome Very Happy
0 Replies
 
satt fs
 
  1  
Reply Wed 10 Nov, 2004 03:42 am
If your are sure that for sufficiently large w

e^(pw) > (1+pw+(1/2)p^2w^2)

for p>0, then you can prove your assertion 2 without recoursing to the L'hospital's rule.
0 Replies
 
Butterfryby
 
  1  
Reply Wed 10 Nov, 2004 04:52 pm
Thanks
I eventually got the answer and the right one for a change and it was a bit less confusing. Thanks for the effort though. I just wish my mathematical side of my brain would decide to kick in before 2 a.m. Now that that's done I wish everyone a happy Veteran's Day and wish myself a good day to study for a physics test.
0 Replies
 
Vengoropatubus
 
  1  
Reply Wed 10 Nov, 2004 04:55 pm
It seems to me as if you're in the wrong set of fields...
0 Replies
 
engineer
 
  1  
Reply Thu 11 Nov, 2004 02:22 pm
The limit is not zero!
The answer to this is e^AB. I put the details in another post in the mathmatics section, but I hope you don't put zero on your test!
0 Replies
 
visk
 
  1  
Reply Sat 20 Nov, 2004 04:14 am
Quote:
for p>0, then you can prove your assertion 2 without recoursing to the L'hospital's rule


I do believe it's L'Hopital's rule. Without the s. Apart from that I've done only done calculus in school and haven't started university yet so I can't make any further comments.
0 Replies
 
visk
 
  1  
Reply Sat 20 Nov, 2004 04:16 am
"Done only done"?
I'm sure you all realise I meant "only done."
Anyway
0 Replies
 
 

Related Topics

Evolution 101 - Discussion by gungasnake
Typing Equations on a PC - Discussion by Brandon9000
The Future of Artificial Intelligence - Discussion by Brandon9000
The well known Mind vs Brain. - Discussion by crayon851
Scientists Offer Proof of 'Dark Matter' - Discussion by oralloy
Blue Saturn - Discussion by oralloy
Bald Eagle-DDT Myth Still Flying High - Discussion by gungasnake
DDT: A Weapon of Mass Survival - Discussion by gungasnake
 
  1. Forums
  2. » L'hospital's Rules tricky proofs need help
Copyright © 2024 MadLab, LLC :: Terms of Service :: Privacy Policy :: Page generated in 0.04 seconds on 05/18/2024 at 03:39:10