integral (from 0 to infinite) of e^(-2x) / sqrt(x). i tried letting u = sqrt(x) so that x = u^2 and dx = 2u du and that turned my integral into 2 integral (from 0 to infinite) of e^(-2u^2) du. how would you do this integral? i checked wolfram alpha and it showed something about the error function but it didn't show the steps.