Askor mentioned: I thought trigonometric substitution only get the job done if there is out there a square root for instance ##sqrt x^2 + two ##. No. Trig substitution is useful if you have the sum or variance of squared terms - they don't need to be within a sq. https://gabletoppak.com/customized-mineral-water-bottles-and-packaged-drinking-water-the-future-of-sustainable-packaging-at-gabletop-pak/