I was wondering which method you'd use to take down the following integral: .

I need it to be "killed", so if any of you, inte-killers, are interested, please have fun.

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- Feb 4th 2010, 05:32 PMarbolisTaking down an integral
I was wondering which method you'd use to take down the following integral: .

I need it to be "killed", so if any of you, inte-killers, are interested, please have fun. - Feb 4th 2010, 06:34 PMSoroban
Hello, arbolis!

Quote:

.

Let: .

. . Then: .

Substitute: .

. . . . . . . .

Back-substitute: .

. . and we have: .

Now we evaluate from 0 to

When we substitute , we get 0.

We don't substitute . we have to*sneak up*on it.

We substitute , then take limit as gets infinite.

We have: .

. . The first limit is: .

. . The second limit is: .

. . Divide top and bottom by .

Therefore, we have: .

Am I close?

- Feb 4th 2010, 06:34 PMKrizalid
okay then, let's kill it.

well actually, i'll let you to kill it, 'cause you just need to integrate by parts the last integral and you're done. - Feb 5th 2010, 11:36 AMarbolis
Thanks to both! That was helpful.

Having the result, I realize I made an error setting up this integral. It came from an attempt to find the electric field of a semi-infinite charged line. I should have reached .