I'm trying to find the integral of E^-(jx)*x^n from a to infinity, with the assumption that Re[j]>0. However, to test it out I first integrated E^-(jx)*x^2 from 1 to infinity, and substituted the answer that I got by picking j->2, and I got 0.169169. Then, I integrated ^-(jx)*x^n from 1 to infinity, and substituted the answer that I got by saying j->2, n->2, and I got 0.169169. Fine, everything works, but when I integrated E^-(jx)*x^n from a to infinity, and substituted j->2, n->2, a->1, I got -0.580831. It's the previous answers minus three fourths. Why are there any inconsistencies in these answers?! I need to know which is correct, although I'll probably spend hours going through an integral table in the meantime, which is what I hate doing, and is one of the reasons I purchased Mathematica.
Attached is the notebook that I used.
Attachment: bug.nb, URL: ,