Signal equation using signal waveform and Fourier series?
Did you check the usual equations?





Responding to:


  The steps I should follow are 
  
  
  Find $f(x)$ from the signal waveform 
  Compute $a_0$, $a_n$, $b_n$ 
  Put above values into the (2) and see whether I get (1) or not.
  


Essentially, yes.

For your equation to relate to the $f(x)$ in the image above you may want to think about 
$$
w_m = \frac{2\pi 5 m}{100} = \frac{\pi m}{10}
$$

Also note that there needs to be an integer (or rational) ratio between $f_1$ and $f_2$ in your equation (1).