How Do You Solve This Complex Integration Problem?

  • Thread starter Thread starter mahmud_dbm
  • Start date Start date
  • Tags Tags
    Integration
mahmud_dbm
Messages
17
Reaction score
0
I need some help with an Integration. Here's the equation

I = ##\int_0^∞ \frac {x^{n+1}} {1 + x^n} ⋅ e^{-x^2/{2 \sigma^2}} ##

I have tried to solve the equation by simplifying first like
let, ## \frac x {\sqrt 2 \sigma} = v ##, so the ##x = v \sqrt 2 \sigma##
then, ##dx = \sqrt 2 \sigma d v##
Also, let ## {\sqrt 2 \sigma} = m, and \ 1+n = p##

Finally, the integration is simplified as follows

I = ##m^{p+1} \int_0^∞ \frac {e^{-v^2}⋅ v^p} {{1 + v^{p - 1} m^{p - 1}}} dv##

Now i don't know what to do from here!
Thank you in advance for your attention to to this post.
I would appreciate any help.
 
Last edited by a moderator:
Physics news on Phys.org
mahmud_dbm said:
I need some help with an Integration. Here's the equation

I = ##\int_0^∞ \frac {x^{n+1}} {1 + x^n} ⋅ e^{-x^2/{2 \sigma^2}} ##


I have tried to solve the equation by simplifying first like
let, ## \frac x {\sqrt 2 \sigma} = v ##, so the ##x = v \sqrt 2 \sigma##
then, ##dx = \sqrt 2 \sigma d v##
Also, let ## {\sqrt 2 \sigma} = m, and \ 1+n = p##

Finally, the integration is simplified as follows

I = ##m^{p+1} \int_0^∞ \frac {e^{-v^2}⋅ v^p} {{1 + v^{p - 1} m^{p - 1}}} dv##

Now i don't know what to do from here!
Thank you in advance for your attention to to this post.
I would appreciate any help.
I would start with integration by parts, with ##u = \frac{x^n}{1 + x^n}## and ##dv = xe^{-x^2/{2 \sigma^2}} dx##. I don't guarantee that this would work, but that's what I would start with.

Also, in future threads, please don't delete the Homework Template. Its use is required.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
Back
Top