Askor stated: I assumed trigonometric substitution only do the job if there is out there a sq. root including ##sqrt x^two + two ##. No. Trig substitution is useful When you have the sum or variation of squared phrases - they don't need to be inside a sq. root. User https://gabletoppak.com/is-it-legal-to-sell-natural-mineral-water-in-gabletop-cartons-tetra-paks-and-aluminium-cans-in-india/