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Homework Help: Could it be impossible to find derivative by basic definition?

  1. May 19, 2014 #1
    (I am sorry, totally forgot about solving quadratic equations, close the topic please)

    1. The problem statement, all variables and given/known data

    Finding derivative of the equation like F(x) = 5x / (1+x^2) by definition (ƒ(a+h) - f (a))/h is easy (point 2;2), but I got really stuck in finding a way to solve it by basic definition ( f(y) - f(a) )/( x - a ) :(

    It seems to me there are much more such equations. Is there any way to do it?
    Last edited: May 19, 2014
  2. jcsd
  3. May 19, 2014 #2


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    Gold Member

    Isn't that the same thing?
    As far as I know, the basic definition of derivative is:
  4. May 19, 2014 #3
    The same, I just had difficulties with canceling equation derived from y - y1 / x - x1, because I totally forgot about solving quadratic equations:( It seemed strange to me on that moment that I could solve the (f(h) - f(a)) / a, but not another form:) Close the topic please.
  5. May 19, 2014 #4
    Topics are not closed without a good reason.
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