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Math Help - Graphing of rational fn

  1. #1
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    Graphing of rational fn

    The equation as attach below. i have the problem on question (b). i confuse to determine the value of point of inflection because the i have the ans for
    dy/dx = +ve the ans given is dy/dx = -ve. see the circle which i mark.

    for your info, when i substitute x=-2 into dy/dx equation, i have the ans as 1/2 which is a +ve as a ans.

    so i need a guide how the graph look like.


    thank in advise.
    Attached Thumbnails Attached Thumbnails Graphing of rational fn-untitled.jpg  
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  2. #2
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    The problem is that you are neglecting the points of discontinuity at x=-1 and x=2. Look below to see what the graph looks like.

    So, when selecting a point to "test" whether the derivative is positive or negative, you should be sure to pick a point between x=-1 and x=0.
    Attached Thumbnails Attached Thumbnails Graphing of rational fn-msp14519a3degea4f47acb00003f5gi1h1i25ei53f.gif  
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  3. #3
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    Quote Originally Posted by drumist View Post
    The problem is that you are neglecting the points of discontinuity at x=-1 and x=2. Look below to see what the graph looks like.

    So, when selecting a point to "test" whether the derivative is positive or negative, you should be sure to pick a point between x=-1 and x=0.

    tq for your help sir...

    what is the name of the software u are using to plot the above graph???
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  4. #4
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    Quote Originally Posted by nikk View Post
    tq for your help sir...

    what is the name of the software u are using to plot the above graph???
    I used Wolfram Alpha:

    http://www.wolframalpha.com/input/?i=x^3%2F%28%28x%2B1%29%28x-2%29%29
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