Help me please, A0 fourier series for this Sawtooth wave

Question

I need to know for this wave sub zero, the correct answer is a0=-2V/Pi, but I do not know how to get to that answer. Help me please the imagen its the series.

This is the sawtooth wave http://s9.postimage.org/42uc7x0pp/IMG00030_20121012_1152.jpg

Thanks!

Answer 1

http://en.wikipedia.org/wiki/Sawtooth_wave

Asymptotic error of Fourier series partial sum of sawtooth function

$$\{x\}=\frac{1}{2}-\sum_{n=1}^N\frac{\sin 2\pi nx}{\pi n}+O((1+||x||N)^{-1}) = \frac{1}{2}-\sum_{n=1}^\infty\frac{\sin 2\pi nx}{\pi n}$$