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Homework Help: AP Calculus: Limits

  1. Feb 18, 2005 #1
    Here's a limit question which I can't seem to figure out how to do, if someone can explain how to do this one question, I'd greatly appreciate it, as I barely understand this:

    In Excercise 9, a positive number E and the limit L of a function f at a are given. Find a number DELTA such that |f(x) -L| < E if 0 < |x-a| < DELTA

    Excercise 9:
    [tex]\lim_{x \rightarrow 4} 2x = 8; E = 0.1[/tex]

  2. jcsd
  3. Feb 18, 2005 #2


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    Write down what you know and what you need to prove:

    Find a [itex]\delta>0[/itex], such that:
    [tex]|2x-8|<0.1[/tex] whenever [tex]|x-4|<\delta[/tex]

    That's almost always the first step. Simply write it down. The answer may already be obvious from the above expression.
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