Integrate x^(1/2)*e^(-x): Tips & Tricks

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Discussion Overview

The discussion revolves around the integral of the function x^(1/2)*e^(-x) over the interval from -∞ to ∞. Participants explore various methods for tackling the integral, including substitution and considerations of the domain of the function.

Discussion Character

  • Exploratory, Debate/contested, Mathematical reasoning

Main Points Raised

  • One participant expresses difficulty in solving the integral and seeks advice on how to approach it.
  • Another participant suggests using the substitution x=t^2 as a potential method for integration.
  • A participant questions whether the integration is restricted to real numbers, noting that the limits of integration may not be valid in that case.
  • It is pointed out that substituting x=t^2 does not lead to a Gaussian integral, and the integration limits cannot be from -∞ to ∞.
  • One participant proposes breaking the integral into two parts: from -∞ to 0 and from 0 to ∞, indicating that if either part diverges, the entire integral diverges.
  • Another participant reiterates the suggestion to break the integral into two parts, emphasizing that the function is not defined on one of those intervals.

Areas of Agreement / Disagreement

Participants express differing views on the validity of the integration limits and the appropriateness of the substitution method. The discussion remains unresolved regarding the best approach to the integral.

Contextual Notes

There are limitations regarding the domain of the function and the validity of the integration limits, which are not fully addressed in the discussion.

snoweangel27
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I can't seem to figure this integral out
\intx^(1/2)*e^(-x) dx
from -\infty to \infty

I have tried integrating by parts, but that didn't seem to do any good. Does anyone know a good way to start this problem?
 
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Are we restricted to the reals? If so, then the limits of integration are not in the domain.
 
Substituting x=t2 does not yield a Gaussian. As sennyk noted, the integration limits cannot be -infinity to infinity.
 
break the integral into two parts one from -inf to 0 and then 0 to inf...if any of those two intregrals diverge then the whole thing diverges
 
Midy1420 said:
break the integral into two parts one from -inf to 0 and then 0 to inf...if any of those two intregrals diverge then the whole thing diverges

The problem is more that the function isn't even defined on one of those intervals.
 

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