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Homework Help: I'm getting 2 different values for this limit but am i doing it right/

  1. Oct 19, 2005 #1
    Hello everyone, i'm having troubles deciding if this limit does not exist...
    i have the problem and work here, i get 2 different limits by letting x and y go to different points and making z fixed at 0. Did i break any rules?

    http://img426.imageshack.us/img426/1372/lastscan7fk.jpg [Broken]
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Oct 20, 2005 #2

    Tom Mattson

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    You forgot to indicate your parameterization in the second attempt. What was it?
  4. Oct 20, 2005 #3


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    It seems to have been (t,t,0).
  5. Oct 20, 2005 #4
    correct (t,t,0)
  6. Oct 20, 2005 #5


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    Yes, in order for the limit to exist, f(x,y,z) must be close to that limit when (x,y,z) are close to 0, no matter how you approach (0,0,0). Since you get two different limits approaching along two different lines, this limit does not exist.
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