Askor reported: I believed trigonometric substitution only do the job if there is offered a sq. root for instance ##sqrt x^two + 2 ##. No. Trig substitution is useful Should you have the sum or big difference of squared conditions - they need not be inside of a sq. root. https://gabletoppak.com/glass-bottles-for-beer-soda-and-even-water-found-to-contain-toxic-levels-of-cancer-linked-microplastics-than-plastic-bottles-study-says/