Askor explained: I thought trigonometric substitution only get the job done if there is offered a sq. root for example ##sqrt x^2 + 2 ##. No. Trig substitution is helpful if you have the sum or change of squared conditions - they need not be inside a square root. In https://gabletoppak.com/how-gable-top-pak-can-enhance-your-brand-and-customer-experience/