Askor claimed: I thought trigonometric substitution only function if there is available a square root including ##sqrt x^2 + two ##. No. Trig substitution is useful In case you have the sum or big difference of squared conditions - they don't need to be within a sq. root. Entrance Gable: https://gabletoppak.com/choosing-between-gable-top-packaging-and-plastic-bottles-for-your-beverage-business/