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Question about functions

  1. Sep 29, 2013 #1

    I am curious, suppose I have a function of x, f(x). Suppose I also have another function P(x). Does this mean I am allowed to have f(P) and I can do standard methods of integration and such on it?
  2. jcsd
  3. Sep 29, 2013 #2
    If P is the variable that you are integrating. For example, [itex]\int \sin(x^2) d(x^2)[/itex] can be computed the way it seems you want to compute it. That is, [itex]\int \sin(x^2) d(x^2) = - \cos(x^2) [/itex]. However, [itex]\int \sin(x^2) dx \neq - \cos(x^2)[/itex]. The question you are asking has a lot to do with the integration method known as "u-substitution." Do you know what that is?
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