(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

I'm trying to understand the solution to this integral

[itex]\int_{\mathbb{R}^3} \frac{e^{i \mathbf{x} \cdot \mathbf{a}}}{\sqrt{r^2+1}}d\mathbf{x}[/itex]

where [itex]d\mathbf{x} =dxdydz, r = \sqrt{x^2+y^2+z^2},\mathbf{a}\in \mathbb{R}^3[/itex]

3. The attempt at a solution

[itex]\int_{\mathbb{R}^3} \frac{e^{i \mathbf{x} \cdot \mathbf{a}}}{\sqrt{r^2+1}}d\mathbf{x} = 2\pi \int_0^{\infty}\frac{1}{\sqrt{r^2 +1}}\frac{e^{iua}-e^{-iua}}{iua}u^2du[/itex]

Could anyone please explain to me how this first step was obtained?

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# Homework Help: Volume integral

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