Askor claimed: I believed trigonometric substitution only function if there is obtainable a square root including ##sqrt x^2 + 2 ##. No. Trig substitution is helpful For those who have the sum or change of squared terms - they need not be within a sq. root. That is supported by https://gabletoppak.com/beyond-beverages-gable-top-cartons-the-versatile-customized-packaging-solution/