Askor mentioned: I thought trigonometric substitution only work if there is accessible a sq. root which include ##sqrt x^two + 2 ##. No. Trig substitution is useful if you have the sum or variation of squared conditions - they don't need to be within a sq. root. This is certainly https://gabletoppak.com/why-every-home-should-use-long-lasting-oil-storage-cartons-for-daily-cooking/