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Math Help - Having trouble with simple integral :/

  1. #1
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    Having trouble with simple integral :/

    It is the integral from 4 to 5 of t times square root of (t-4)

    I tried integrating parts but did not come up with the correct answer. This is so simple I don't understand why I can't get this.

    Thanks for the help.
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  2. #2
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    Re: Having trouble with simple integral :/

    Try the substitution u= t- 4. Then t= u+4 so [itex]t\sqrt{t- 4}= (u+4)u^{1/2}[/tex]. Don't forget to change the limits of integration: when t= 4, what is u? When t= 5, what is u?
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  3. #3
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    Re: Having trouble with simple integral :/

    Great! I did that substitution and it worked! I got the right answer. For learning purposes though, why couldn't I use integration by parts here?

    Thanks.
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