Askor stated: I thought trigonometric substitution only get the job done if there is offered a sq. root for example ##sqrt x^2 + two ##. No. Trig substitution is helpful if you have the sum or change of squared phrases - they don't need to be within a square root. https://gabletoppak.com/kerala-get-ready-to-say-no-to-plastic-from-october-2/