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Limit of 1/x + 1/x^2 when x -> 3 from the left

  1. Mar 14, 2005 #1
    Just want to check my answers...
    are my answers right?

    1) lim (1/x) + (1/x^2)
    x-> 3-
    ans=0

    2) lim √(x^2+4)-2/x
    x->0
    ans=0

    3) lim (√(2x^2+5) -x)
    x-> positive infinity
    ans= positive infinity
     
  2. jcsd
  3. Mar 14, 2005 #2
    1) and 2) are wrong.

    3) is right.

    First let's check that I understand your questions right. Are these the limits you're trying to find?

    [tex] \lim_{x\rightarrow 3^-} \left(\frac{1}{x} + \frac{1}{x^2}\right)[/tex]

    [tex] \lim_{x \rightarrow 0} \left( \sqrt{x^2 + 4} - \frac{2}{x}\right)[/tex]

    [tex] \lim_{x \rightarrow \infty} \left( \sqrt{2x^2 + 5} - x \right)[/tex]


    If so, why don't you show us the work you did for the first two.
     
  4. Mar 14, 2005 #3
    the second one is √(x^2+4)-2 all over x
    how about you tell me the correct answer...and i'll try to find my mistake?
     
  5. Mar 14, 2005 #4

    HallsofIvy

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    Staff Emeritus
    Science Advisor

    I doubt that just being given the answer would help you.

    I don't think it's a matter of finding your mistake: I get the impression you have no idea what to do- the first problem, for example is just a matter of evaluating the function. If you can't do that, you certainly can't do the others.

    Show us how you attempted them. Then we can see what kind of help you need.
     
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