Askor mentioned: I believed trigonometric substitution only operate if there is on the market a square root which include ##sqrt x^two + two ##. No. Trig substitution is useful When you have the sum or big difference of squared terms - they don't need to be inside a sq. root. https://gabletoppak.com/why-every-home-should-use-long-lasting-oil-storage-cartons-for-daily-cooking/