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Thread: the formal definition of limit

  1. December 1st 2009, 02:57 PM #1
    koko2009
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    the formal definition of limit

    Let
    f :®  be given by f ( x) = x2 - 4 . Then lim

    x
    ®-3

    ( x^2 - 4) = 5.
    any help will be appraciated,thanks.
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  2. December 1st 2009, 05:18 PM #2
    Drexel28
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    Quote Originally Posted by koko2009 View Post
    Let

    f :®  be given by f ( x) = x2 - 4 . Then lim


    x
    ®-3
    ( x^2 - 4) = 5.
    any help will be appraciated,thanks.
    \left|x^2-4-5\right|=\left|x-3\right|\left|x+3\right|. Now if we only consider a neighborhood of radius 1 (i.e. 0<|x+3|<1 then we can say that |x-3|<c for some c (find it). Do you get the idea?
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