Askor said: I thought trigonometric substitution only function if there is obtainable a square root including ##sqrt x^2 + 2 ##. No. Trig substitution is helpful When you have the sum or big difference of squared terms - they don't need to be inside of a sq. root. The gable https://gabletoppak.com/sustainability-in-action-gable-top-cartons-to-save-our-oceans/