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: Confusing Limits

  1. Jun 19, 2011 #1
    1. The problem statement, all variables and given/known data

    1. limh->0 (sqrt(a+h)-sqrt(a))/h
    2. limx->1 (1-sqrt(x))/(1-x)

    2. Relevant equations

    ---------------------------------------------

    3. The attempt at a solution

    I tried conjugate, etc., but couldn't solve it without L'H's Rule.
     
  2. jcsd
  3. Jun 19, 2011 #2

    vela

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Education Advisor

    Using the conjugate will work. What did you get when you tried that?
     
  4. Jun 19, 2011 #3
    Thanks I got 1/(2)for one and 1/2 for number 2
     
    Last edited: Jun 19, 2011
  5. Jun 19, 2011 #4

    Char. Limit

    User Avatar
    Gold Member

    For the second one, try factoring the numerator like so:

    [tex]1 - x =\left(1 - \sqrt{x}\right)\left(1 + \sqrt{x}\right)[/tex]

    The solution should then become obvious.

    EDIT: And for the first one, multiplying by the conjugate of the numerator is what you need to do.
     
  6. Jun 20, 2011 #5
    Thanks guys, got them.

    Ignore my comment above this.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook