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Graph limits

  1. Oct 12, 2015 #1
    Let f be a function on [0,major infinity] such that for each point in its graph,(x,y)=(y*y,y).At how many points must each point in f have a limit....?

    I'm not clear what the question is aiming...
  2. jcsd
  3. Oct 12, 2015 #2


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    It's a mystery to me! I think "major infinity" must be a translation error but I have no idea what "each point in f has a limit" could mean. In what sense does a point have a limit?
  4. Oct 12, 2015 #3


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    Hello Zhang, welcome to PF :smile: !

    You are not the only one for whom this question is unclear (witness faster typing Ivy's comment!)
    My impression is that the problem statement is not quite complete: there remain a lot of questions (some of which may be answered from the context):

    Normally functions are a mapping from a domain to an image (or codomain or range).

    Your function maps ## x \in [0,\infty]## to what ?
    If for each point in its graph x = y^2 that would mean ## f: \ x\rightarrow \sqrt x\ ## and then the question
    can easily be answered with "at infinitely many points", but that probably wasn't intended by the exercise writer. He/she may have had in mind one of several possibilities:
    1. for all x in the domain ## x \in [0,\infty]##
    2. idem, except ....
    3. still something else
    so my return question is: what is discussed in the section/chapter/episode where this exercise is given ?

    By the way: I don't believe this "At how many points must each point in f" is literally quoted ... :rolleyes:
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