My table of Integrals has the general case ##int frac dx x^2+a^2 ## like a 'common' integral far too, not merely the situation where by ##a=one##. But I do think this being a Calculus homework problem it is expected from the OP to figure out how to get it done. https://gabletoppak.com/customized-mineral-water-bottles-and-packaged-drinking-water-the-future-of-sustainable-packaging-at-gabletop-pak/