1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Find the limit

  1. Sep 4, 2008 #1
    1. The problem statement, all variables and given/known data
    2. Find the limit.

    2. Relevant equations
    No clue, that's why I am asking.

    3. The attempt at a solution
    I inverted the signs and multiplied by sqrt(x^1+1)+1
    sqrt(x^2+1)-1 sqrt(x^2+1)+1
    --------------- * --------------
    -(x^2) sqrt(x^2+1)+1
    and came up with
    which gave me

    I am sure this isn't correct, but I do not know were I messed up.
  2. jcsd
  3. Sep 4, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper

    (sqrt(x^2+1)-1)*(sqrt(x^2+1)+1)=(x^2+1)-1. Now isn't it? Not (x+1)-1. As (a+b)*(a-b)=a^2-b^2?
  4. Sep 5, 2008 #3
    when i graphed it, i found the answer to be
    infinity - infinity*i
    none of those answer sound like what a teacher would be looking for, so i would guess the answer is either "limit does not exsist" or you copied the problem wrong
  5. Sep 5, 2008 #4


    User Avatar
    Staff Emeritus
    Science Advisor

    Your method is perfectly good. You algebra needs some work!
    First you can't just change the x^2- 1 inside the square root into x^2+ 1 by "inverting the sign". Second, (1- sqrt(x^2+ 1))(1+ sqrt(x^2+ 1))= 1- (x^2+11)= -x^2.

    In any case, if you just let x= 0 in the original form, you get (1- i)/0. Since the numerator is not 0, that limit does not exist.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Find the limit
  1. Find the Limit (Replies: 3)

  2. Find the limit (Replies: 15)

  3. Finding the Limit? (Replies: 1)

  4. Find the limit (Replies: 26)

  5. Find this limit? (Replies: 4)