How do you integrate this function (not by parts)?

zheng89120
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Homework Statement



integrate: r2*exp(i*k*r - r2/a2) from -infinity to +infinity (in terms of r)

Homework Equations



relevant integration table

The Attempt at a Solution



not sure what this function or the method to solve this function is called
 
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I would start by completing the square in the exponential, and then changing variables to y = r - b, where b is whatever you get when you complete the square. Then, use know results for the integrals of Gaussian functions.
 
Without going through the whole exercise, the thing that comes to mind is splitting off a square. I think that eventually you will find a substitution like z = r/a - \tfrac12 i a k which will allow you to write it in terms of integrals like
\int e^{z^2} and \int z e^{z^2}
which you can do without partial integration.
 
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...

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