My desk of Integrals has the final situation ##int frac dx x^two+a^2 ## as a 'common' integral much too, not just the case exactly where ##a=1##. But I think this being a Calculus research dilemma it is expected of the OP to determine how to get it done. Hints were https://gabletoppak.com/the-growing-threat-of-marine-pollution-and-how-gabletop-cartons-offer-a-solution/