My Desk of Integrals has the final case ##int frac dx x^two+a^two ## as a 'regular' integral too, not simply the situation exactly where ##a=1##. But I believe this remaining a Calculus homework trouble it is expected with the OP to figure out how to get it done. Hints got https://gabletoppak.com/glass-bottles-for-beer-soda-and-even-water-found-to-contain-toxic-levels-of-cancer-linked-microplastics-than-plastic-bottles-study-says/