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Tangent of a graph

  1. Feb 15, 2007 #1

    disregardthat

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    Is is possible to calculate the growth-rate to a tangent in a graph? (like f(x)=x^2

    I only know how to draw the line on the graph, but how do you calculate it if you know the point where you must draw the tangent?

    For example: find the tangent of the point x=2 on a graph f(x)=x^2

    How do you find the rate of growth?
     
  2. jcsd
  3. Feb 15, 2007 #2

    mathman

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    This is one of the first things you learn about in elementary calculus. The tangent (slope) at a point on a curve is given by the first derivative at that point.
     
  4. Feb 15, 2007 #3

    disregardthat

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    I have only had one class in calculus, and we learned the average rate of change. Then we got two points in a graph, and calculated the average slope. I know what a tangent of a graph is, and I have managed to sort out the somewhat accurate answer with only drawing the line, but I don't know how to calculate it.

    And what is a derivative? Is a derivative the average slope for two points of the x-axis on a graph?
     
  5. Feb 15, 2007 #4
    Your are talking about the whole limiting process that the derivative is. You will eventually learn how to calculate the slope of the tangent with analytical methods if you follow a calculus course.
     
  6. Feb 15, 2007 #5

    disregardthat

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    Man!

    :tongue2:
     
  7. Feb 16, 2007 #6
    The slope here for x=2 is 4.If you take the derivative of f(x)=x^2,you get dy/dx=2x

    now substitute the value of x and you get the slope!
     
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