My table of Integrals has the general case ##int frac dx x^two+a^two ## being a 'common' integral way too, not only the case where ##a=one##. But I feel this currently being a Calculus homework issue it is expected of the OP to figure out how to get it done. Hints https://gabletoppak.com/reducing-microplastics-why-gable-top-cartons-are-better-than-plastic-water-bottles/