Askor said: I believed trigonometric substitution only work if there is available a sq. root including ##sqrt x^2 + two ##. No. Trig substitution is useful When you've got the sum or variance of squared phrases - they needn't be within a square root. Gabletop Pak delivers an in depth https://gabletoppak.com/bioplastics-greenwashing-or-genuine-solution-the-truth-behind-the-hype/