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Homework Help: Find primitives of function (1+4x)/sqrt(1 + x + 2x^2)

  1. Nov 16, 2006 #1
    This is a practice exam question that I have been given!
    Find the primitives of the functions
    (1+4x)/(sqrt(1+x+2x^2))

    My question is 1. is a primitive the antiderivative? I dont remember my lecturer using primitive during our course!
     
  2. jcsd
  3. Nov 16, 2006 #2
    It is basically asking you to find:

    [tex] \int \frac{1+4x}{\sqrt{1+x+2x^{2}}} \; dx [/tex]

    A primitive is an antiderivative.

    So set [tex] u = 1+x+2x^{2} [/tex]

    Then [tex] du = 4x+1 \; dx [/tex] and you end up with [tex] \int u^{-\frac{1}{2}} \; du [/tex]. All the primitives mean that you add the integration constant [tex] C [/tex].
     
    Last edited: Nov 16, 2006
  4. Nov 16, 2006 #3
    ahhh thanks!
     
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