Finding definite Integral Help

Limits, differentiation, related rates, integration, trig integrals, etc.
jdom543
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Finding definite Integral Help

Postby jdom543 » Mon Aug 16, 2010 12:22 am

I need to find the definite integral of f(x)=xe^(4x) on the closed interval [-2,2]

I just recently learned how to find definite integrals but most of the ones I've learned weren't like this and are easier at least at first glance (Unless I'm missing something). I know how to use substitution and what not, but I don't see anything here to substitute to make the problem simpler. Thanks

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Martingale
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Re: Finding definite Integral Help

Postby Martingale » Mon Aug 16, 2010 12:28 am

jdom543 wrote:I need to find the definite integral of f(x)=xe^(4x) on the closed interval [-2,2]

I just recently learned how to find definite integrals but most of the ones I've learned weren't like this and are easier at least at first glance (Unless I'm missing something). I know how to use substitution and what not, but I don't see anything here to substitute to make the problem simpler. Thanks





use integration by parts

jdom543
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Re: Finding definite Integral Help

Postby jdom543 » Mon Aug 16, 2010 12:36 am

Martingale wrote:
jdom543 wrote:I need to find the definite integral of f(x)=xe^(4x) on the closed interval [-2,2]

I just recently learned how to find definite integrals but most of the ones I've learned weren't like this and are easier at least at first glance (Unless I'm missing something). I know how to use substitution and what not, but I don't see anything here to substitute to make the problem simpler. Thanks





use integration by parts

I haven't learned that yet. At least I don't think I guess I'll google/youtube it for a video on it. Thanks

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Martingale
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Re: Finding definite Integral Help

Postby Martingale » Mon Aug 16, 2010 12:38 am

jdom543 wrote:I haven't learned that yet. At least I don't think I guess I'll google/youtube it for a video on it. Thanks


http://www.youtube.com/watch?v=dqaDSlYdRcs

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stapel_eliz
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Postby stapel_eliz » Mon Aug 16, 2010 1:11 pm

jdom543 wrote:I know how to use substitution and what not....
Martingale wrote:use integration by parts
jdom543 wrote:I haven't learned that yet.

What methods have you learned?

Thank you! :wink:

jdom543
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Re:

Postby jdom543 » Mon Aug 16, 2010 5:28 pm

stapel_eliz wrote:
jdom543 wrote:I know how to use substitution and what not....
Martingale wrote:use integration by parts
jdom543 wrote:I haven't learned that yet.

What methods have you learned?

Thank you! :wink:

The method that I learn usually only involved substitution of one term and then when you decide by the reciprocal derivative of that term it cancels out other terms in the integrand making it much easier to simplify. I've also know about substitution using Trig identities. And now I know Integration by parts since I looked up a video regarding it. :D


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