Askor mentioned: I thought trigonometric substitution only function if there is on the market a square root like ##sqrt x^2 + 2 ##. No. Trig substitution is helpful When you've got the sum or big difference of squared terms - they don't need to be inside a sq. root. Explore https://gabletoppak.com/boost-brand-visibility-with-customized-packaged-drinking-water/