# How do you find the complex $(C_n)$ fourier series expansion of $e^{ax}$?

How do you find the complex $$(C_n)$$ fourier series expansion of $$e^{ax}$$? The period of the function is 2$$\pi$$. I've tried to do this question out several times, and I keep getting stuck and don't know how to proceed.

I have got to the point $$C_n$$ = $$\frac{1}{2\pi}$$[$$\frac{-1^n(e^{a \pi}-e^{-a \pi}) }{a-in}$$]

I am not sure where to proceed from here

• You need to specify an interval. You then simply apply the definition and then integrate. What is the confusion? – user9464 Jan 16 at 19:08
• Do you know what a Fourier series is? – user9464 Jan 16 at 19:09
• Welcome to Math SE! It would be most helpful if you would edit your question to show us your own attempts. See the Mathjax tutorial for information about displaying math correctly on this site. – DMcMor Jan 16 at 19:20
• @dk1233 - put those remarks in your question rather than just in the comments. People are not necessarily going to take the time to read all the comments and as it stands your question is lacking some necessary context. – DMcMor Jan 16 at 19:24
• @DMcMor okay will do, thanks for the adivce – mathslover Jan 16 at 20:20