Askor explained: I assumed trigonometric substitution only get the job done if there is offered a sq. root for example ##sqrt x^2 + 2 ##. No. Trig substitution is helpful For those who have the sum or change of squared conditions - they don't need to be within a sq. https://gabletoppak.com/bioplastics-greenwashing-or-genuine-solution-the-truth-behind-the-hype/