Askor said: I thought trigonometric substitution only do the job if there is out there a square root including ##sqrt x^two + 2 ##. No. Trig substitution is helpful When you've got the sum or change of squared terms - 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/