Askor claimed: I assumed trigonometric substitution only do the job if there is available a square root such as ##sqrt x^2 + two ##. No. Trig substitution is helpful When you've got the sum or big difference of squared phrases - they don't need to be inside a sq. root. https://gabletoppak.com/sustainability-in-action-gable-top-cartons-to-save-our-oceans/