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Math Help - Graphing a funcion

  1. #1
    Junior Member
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    Graphing a funcion

    Graph the function.

    y=20\left(\frac{1}{4}\right)^{x}

    Is this table correct?

    x/ f(x)
    -3/ 1280
    -2/ 320
    -1/ 80
    0/ 20
    1/ 5
    2/ (4/5)
    3/ (5/16)


    Also...how could I graph this by hand so that everyhting fits?

    Thanks!
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  2. #2
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    errr your f(2) is wrong...

    and to draw that you... get paper... and do dots :P and then do a lineee hehe =D

    yer so ... make it the x values from say -3 to 3 and y from say... 1300 to ... 0?
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  3. #3
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    Oh, you're right. It should be (5/4). Thanks for pointing it out (:
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  4. #4
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    Hello, mt_lapin!

    Graph the function: . y\:=\:20\left(\frac{1}{4}\right)^{x}

    Is this table correct?

    . . \begin{array}{c|c}<br />
x & f(x) \\ \hline -3&1280 \\ -2&320 \\ -1&80 \\ 0&20 \\ 1&5 \\ 2&\frac{4}{5} \\3 & \frac{5}{16} \end{array} . . . . . Yes!


    Also...how could I graph this by hand so that everything fits?
    Normally, no one expects a truly accurate graph.


    Assuming that we know the shape of: . [1]\;\;y \:=\:a^x
    . . we can sketch: . [2]\;\;y \:=\:20\cdot4^{-x}

    It is basically a reflection of [1] over the y-axis.


    Code:
              *       |
                      |
               *      |
                *     |
                 *    |
                   *  |
                      *20
                      |     *
                      |               *
          - - - - - - + - - - - - - - - -
                      |
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  5. #5
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    Thank you so much Soroban! You've been a lot of help
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