Math Is Fun Forum

almost there

Member

Registered: 2009-11-11

Posts: 21

integrating with e

I'm just not sure how to come at this. Usually with things that look this way I use a substitution, but any way I try a substitution, I have a factor of "x" in the du-expression that is supposed to be substituted for "dx" (which, to my understanding, ought to be "x-free"). I need to be able to handle integrals like this one for homework, but have an exam coming soon as well and there will be lots of similar integrals. What is a good approach?

Last edited by almost there (2009-11-23 09:08:16)

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: integrating with e

Hi almost there;

You probably won't be asked to handle integrals exactly like this one for homework as I don't think it can be done analytically.

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

almost there

Member

Registered: 2009-11-11

Posts: 21

Re: integrating with e

Thank you very much for your confirmation--I really didn't see a viable point-of-entry on this one, but its been so long since I've done calculus that I thought maybe I was missing something.

Interestingly enough, almost this exact integral appears on a homework assignment for my probability course. I had only posed this integral initially to check my understanding of the calculus relevant to the problem. I will post the original problem as a new topic (since it apparently is).

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: integrating with e

Hi almost there;

Almost this exact integral can make a big difference.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.