Askor stated: I assumed trigonometric substitution only do the job if there is out there a sq. root including ##sqrt x^two + 2 ##. No. Trig substitution is helpful if you have the sum or change of squared phrases - they don't need to be inside of a square root. https://gabletoppak.com/why-gable-top-cartons-are-making-a-splash-in-the-water-industry/