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Homework Help: Intergrating e

  1. Aug 1, 2008 #1
    intergrating "e"

    I'm doing some intergration q's and I'm stuck on one which involves e

    [x^2 e^(x^3) ]dx

    I know to integrate you "add one to the power and divide by the new power.. would that make the solution

    ((x^3)/3) ((e^(x^4))/(x^4)? hope that makes a bit of sense..
  2. jcsd
  3. Aug 1, 2008 #2
    Re: intergrating "e"

    try u substition
  4. Aug 1, 2008 #3


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    Re: intergrating "e"

    Nope it doesn't really make sense

    [tex]\int f(x)g(x)dx\neq \int f(x)dx \int g(x)dx [/tex]
    [tex]\int e^{x^n}dx \neq \frac{e^{x^{n+1}}}{x^{n+1}}[/tex]

    That sort of rule only works for the forms x^n and not anything else. The "only" way to integrate an exponential, is to use [tex]\int e^xdx = e^x[/tex]. In this case, you can't do that directly, but a substituion u = x^3 should do the trick.
    Last edited: Aug 1, 2008
  5. Aug 1, 2008 #4
    Re: intergrating "e"

    great - cheers for that i get it now :)
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