My table of Integrals has the overall situation ##int frac dx x^two+a^2 ## being a 'normal' integral way too, not merely the situation where ##a=one##. But I believe this being a Calculus research difficulty it is expected of the OP to figure out how to do it. Hints were given https://gabletoppak.com/from-plastic-bottles-to-gabletop-cartons-a-step-toward-solving-the-plastic-pollution-crisis/