Math Is Fun Forum
You are not logged in.
- Topics: Active | Unanswered
Pages: 1
#1 2007-05-01 21:49:52
- rootz
- Guest
L hopitals rule
hey everyone!
can some please check this for me. Thank you
lim x-->0
xcosx / sin2x = 0/0
-xsinx+cosx / 2cos2x = 0+1/2.1 = 1/2
is this correct?
#2 2007-05-01 22:32:04
- mathsyperson
- Moderator
- Registered: 2005-06-22
- Posts: 4,900
Re: L hopitals rule
Flawlessly. 
Why did the vector cross the road?
It wanted to be normal.
Offline
#3 2007-05-05 04:49:35
- HallsofIvy
- Guest
Re: L hopitals rule
hey everyone!
can some please check this for me. Thank you
lim x-->0
xcosx / sin2x = 0/0
-xsinx+cosx / 2cos2x = 0+1/2.1 = 1/2
is this correct?
Yes, though using L'Hopital is a bit of "over-kill". Rewrite that as
If you know the derivative of sin x you certainly should recognize that the limit of is 1.#4 2007-05-05 04:51:25
- HallsofIvy
- Guest
Re: L hopitals rule
rootz wrote:hey everyone!
can some please check this for me. Thank you
lim x-->0
xcosx / sin2x = 0/0
-xsinx+cosx / 2cos2x = 0+1/2.1 = 1/2
is this correct?
Yes, though using L'Hopital is a bit of "over-kill". Rewrite that as
If you know the derivative of sin x you certainly should recognize that the limit of is 1.
Oops I meant, of course,
which will give 1/2 as limit. Is there anyway to edit posts on this forum?#5 2007-05-05 10:14:24
- MathsIsFun
- Administrator
- Registered: 2005-01-21
- Posts: 7,711
Re: L hopitals rule
Hi HallsOfIvy ... sign up!
"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman
Offline
Pages: 1