Results 1 to 4 of 4

Math Help - L'Hopital

  1. #1
    Junior Member
    Joined
    Oct 2008
    Posts
    42

    L'Hopital

    when finding the limit as x approaches zero of a vector, when plugging in zero, I get (1/2)i + 0j + 0k

    On my test I wrote the limit is 1/2 but my teacher circled 0j+0k and wrote "use L'Hopital." Does this mean the limit is 0 since two of the three terms go to 0?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member redsoxfan325's Avatar
    Joined
    Feb 2009
    From
    Swampscott, MA
    Posts
    943
    Quote Originally Posted by cottekr View Post
    when finding the limit as x approaches zero of a vector, when plugging in zero, I get (1/2)i + 0j + 0k

    On my test I wrote the limit is 1/2 but my teacher circled 0j+0k and wrote "use L'Hopital." Does this mean the limit is 0 since two of the three terms go to 0?
    What was the original problem?
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Oct 2008
    Posts
    42
    find the limit as x approaches 0 of [(2x+3)/(x^2+6)]i + [(sin(x)/x]j + [(e^x) -1]k
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Super Member redsoxfan325's Avatar
    Joined
    Feb 2009
    From
    Swampscott, MA
    Posts
    943
    Quote Originally Posted by cottekr View Post
    find the limit as x approaches 0 of [(2x+3)/(x^2+6)]i + [(sin(x)/x]j + [(e^x) -1]k
    \lim_{x\to0}\frac{\sin x}{x}=1, not 0.

    To see this, use L'Hopital's Rule (because we have the \frac{0}{0} case):

    \lim_{x\to0}\frac{\sin x}{x}=\lim_{x\to0}\frac{\cos x}{1}=1

    So the answer is \frac{1}{2}\hat{i}+\hat{j}.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Need some help with L'Hopital's.
    Posted in the Calculus Forum
    Replies: 3
    Last Post: March 10th 2011, 11:14 AM
  2. L'Hopital lim (x->0) (a^x-1)/x
    Posted in the Calculus Forum
    Replies: 2
    Last Post: June 23rd 2010, 11:57 PM
  3. needs l'hopital can you help
    Posted in the Calculus Forum
    Replies: 1
    Last Post: October 18th 2009, 04:20 PM
  4. L'Hopital
    Posted in the Calculus Forum
    Replies: 2
    Last Post: November 15th 2008, 05:19 AM
  5. L'Hopital
    Posted in the Calculus Forum
    Replies: 4
    Last Post: November 9th 2008, 04:45 PM

Search Tags


/mathhelpforum @mathhelpforum