Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Limit question !

  1. Jan 6, 2012 #1
    1. The problem statement, all variables and given/known data

    I know it needs L'Hopital but i can't get it to the indeterminant form

    Limit (x-(x+2)e^(1/x)) ((inf - inf ))
    x-->inf

    I reached until here and then i got stuck

    (1-((x+2)e^(1/x))/x)/(1/x) (1 -inf/inf)/0
     
  2. jcsd
  3. Jan 6, 2012 #2

    Curious3141

    User Avatar
    Homework Helper

    Separate limit into [itex]\lim_{x \rightarrow \infty} x(1 - e^{\frac{1}{x}}) - 2e^{\frac{1}{x}}[/itex].

    Second term is easy.

    First term is indeterminate of the form infinity*0, so reexpress it as [itex]\frac{1 - e^\frac{1}{x}}{\frac{1}{x}}[/itex], then let [itex]y = \frac{1}{x}[/itex] and take the limit as [itex]y \rightarrow 0[/itex] using L' Hopital's Rule.
     
  4. Jan 6, 2012 #3
    Oh i see :D !! Thanks alot :)
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook