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Math Help - U-sub or integration by parts?

  1. #1
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    U-sub or integration by parts?

    I have this equation here...

    (x/3)e^(x^2)

    I'm thinking I have to take this in parts, am I right?
    since isn't integration by parts the anti - product rule? and I see two products of x in this...

    or am I totally wrong?

    if it IS integration by parts....
    which do I choose for u and dv

    I think I have u = (1/3)x
    du = 1/3dx
    dv = x^2
    v = (1/3)x^3

    Will this work? I need to know how to recognize between u-sub and integration by parts and WHAT to take...
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  2. #2
    MHF Contributor harish21's Avatar
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    Quote Originally Posted by RET80 View Post
    I have this equation here...

    (x/3)e^(x^2)

    I'm thinking I have to take this in parts, am I right?
    since isn't integration by parts the anti - product rule? and I see two products of x in this...

    or am I totally wrong?

    if it IS integration by parts....
    which do I choose for u and dv

    I think I have u = (1/3)x
    du = 1/3dx
    dv = x^2
    v = (1/3)x^3

    Will this work? I need to know how to recognize between u-sub and integration by parts and WHAT to take...
    \int \frac{x}{3} e^{x^2} dx = \frac{1}{3} \int x \times e^{x^2} dx

    use substitution, not integration by parts.
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  3. #3
    MHF Contributor

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    Quote Originally Posted by RET80 View Post
    I have this equation here...

    (x/3)e^(x^2)

    I'm thinking I have to take this in parts, am I right?
    since isn't integration by parts the anti - product rule? and I see two products of x in this...

    or am I totally wrong?

    if it IS integration by parts....
    which do I choose for u and dv

    I think I have u = (1/3)x
    du = 1/3dx
    dv = x^2
    v = (1/3)x^3

    Will this work?
    Well, why don't you try it and SEE if it works?
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