Problem # $2(33\mathrm{.}33$ points$)$ Consider an FIR filter described by the following difference equation:

$y(n)=x(n)-x(n-4)$

a$)$ Determine the frequency response $H()$ of the system.

b$)$ Determine the output of the system to the following input signal:

$x(n)=cos(\frac{}{2}n)+cos(\frac{}{4}n),-$