Askor said: I believed trigonometric substitution only do the job if there is offered a sq. root like ##sqrt x^two + two ##. No. Trig substitution is useful In case you have the sum or difference of squared terms - they need not be inside of a sq. root. , https://gabletoppak.com/beyond-beverages-gable-top-cartons-the-versatile-customized-packaging-solution/