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Math Help - need help in completing a table

  1. #1
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    need help in completing a table

    ok i already tried this but i'm not really sure if i did it right at all so i'm looking for some help. heres the problem.(spaces didnt work, i had to use underscores)


    Use the function f(x)=2/x for the following.
    a. Complete the table for x=2

    h_|x+h| f(x+h) | f(x) | f(x+h)-f(x)/h
    1_|___|_______|____|___________
    .5_|___|______|____|___________
    .1_|___|______|____|___________
    .01|___|______|____|___________



    now i completed the table by just plugging in 2 for x on all of the rows, along with the corresponding h value. so mine looks like this.


    _h_|x+h|f(x+h)__|f(x)| f(x+h)-f(x)/h
    _1_|_3_|__2/3__|_1_|-1/5
    .5_|2.5_|__4/5__|_1_|-2/5
    .1_|2.1_|20/21__|_1_|-1/2
    .01|2.01|200/201|_1_|-1/2


    is that the correct way to do it or am i missing something?
    also there are a couple corresponding questions


    b. Find f'(2) by a rule or formula
    i got -1/4 for this

    c. Is there a relationship between parts A and B? If so, what?
    this is where i figured i did the table wrong, because i can't figure out what the relationship is. this is all for an important grade i could really use any help you can give me. thanks.
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  2. #2
    Behold, the power of SARDINES!
    TheEmptySet's Avatar
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    f(x)=\frac{2}{x}=2x^{-1}

    taking the derivative

    f'(x)=-2x^{-2}=\frac{-2}{x^2}

    then evaluate at 2

    f'(2)=\frac{-2}{2^2}=-\frac{1}{2}
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  3. #3
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    yeah i screwed up in typing that one sry.

    im more concerned about the table. ive never had to do anything like that before, it just feels like i did it incorrectly.
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  4. #4
    GAMMA Mathematics
    colby2152's Avatar
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    Quote Originally Posted by sean1058 View Post
    yeah i screwed up in typing that one sry.

    im more concerned about the table. ive never had to do anything like that before, it just feels like i did it incorrectly.
    You did the table correctly. You calculated the value of the derivative via formula wrong. Check out the latest in my Calculus Notes regarding derivatives. I show the tedious method of how to calculate, or estimate, them numerically.
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