# Fouries series integration help

• Sep 22nd 2010, 05:01 AM
Nguyen
Fouries series integration help
Hey everyone, I am stuck on 2 questions, so if anyone can help me that would be much appreciated.

$f(x)=\begin{Bmatrix} 2, & -1

Fourier Series representation:
$f(x)=a_0 + \sum_{n=1}^{\infty}(a_n \cos(\frac{n \pi x}{2}) +b_n \sin(\frac{n \pi x}{2}))$

The first question is to integrate both sides of $f(x)$ from -2 to 2 to show that $a_0=1$.
The second question is to multiply both sides of $f(x)$ by $sin(\frac{m \pi x}{2})$ and integrate from -2 to 2 to show that $b_n=0$.

Because of the domain restrictions on f(x) I can't figure out what to do for these questions.

If you can help me it would be nice. Thanks
• Sep 22nd 2010, 02:30 PM
zzzoak
Integrating F equation
$\int_{-2}^2 f(x) \; dx=\int_{-2}^2 a_0 \; dx$
May be shown that other terms are zeros.
$\int_{-2}^2 f(x) \; dx=\int_{-1}^1 2 \; dx=4$
$\int_{-2}^2 a_0 \; dx=4a_0$
• Sep 22nd 2010, 06:52 PM
Nguyen
Thanks zzzoak, I get question 1, but I still don't understand how to do the 2nd question.