Use the substitution u=1+2exu = 1 + 2e^xu=1+2ex to find ∫e3x1+2exdx\displaystyle \int \frac{e^{3x}}{1 + 2e^x} dx∫1+2exe3xdx.
Practise Edexcel A Level Maths 11.5 Integration by Substitution with exam-style questions for A Level Maths. 59 questions, matched to the Edexcel A Level Maths (9MA0) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.