Askor stated: I assumed trigonometric substitution only work if there is out there a square root such as ##sqrt x^2 + two ##. No. Trig substitution is helpful When you've got the sum or variance of squared terms - they need not be inside of a square root. Photon 'time https://gabletoppak.com/quenching-thirst-building-brands-how-free-water-campaigns-on-gable-top-cartons-create-impactful-brand-awareness/