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Derivative of a sum of functions, also cubic graph roots

  1. Jul 19, 2009 #1
    Derivative of a sum of functions

    What would you interperate this as?

    It is one of the subsections of Differentiation from the syllabus of a University entrance Exam in November but I cannot think what it is refering to.

    Differentiation: Derivative of xa, including for fractional exponents.
    Derivative of a sum of functions. Tangents and normals to graphs. Turning
    points. Second order derivatives. Maxima and minima. Increasing and
    decreasing functions.

    That is the whole section, also, what is a second order derivative? I have done both before as it is based on my first year in college which I have already done but I have never heard them refered to as that before so I am a bit unsure.

    Also, I know when I have a quadratic equation, I can find how many real roots it has, but how would I go about finding this if the graph was a cubic as I cannot use the quadratic equation?

    Thanks alot

  2. jcsd
  3. Jul 19, 2009 #2


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    Hi James! :smile:

    The syllabus starts by defining derivatives of x, x2, x3, and so on, and then shows how to find th derivative of a sum like ax2 + bx + c. :wink:
    The derivative of a derivative (eg d2y/dx2) … this is relevant to finding turning points.
    mmm … wait and find out! :wink:
  4. Jul 19, 2009 #3
    Thanks alot for that, didn't realise that was it, glad they are something easy & not hard.

    I will do a bit of digging on the cubic then and try to work it out ;)
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