Askor reported: I assumed trigonometric substitution only work if there is accessible a square root including ##sqrt x^2 + 2 ##. No. Trig substitution is helpful When you've got the sum or big difference of squared phrases - they needn't be inside a square root. Customization: Being familiar with that https://gabletoppak.com/is-it-legal-to-sell-natural-mineral-water-in-gabletop-cartons-tetra-paks-and-aluminium-cans-in-india/