2.1 (a) The even part of the signal $x[n] = \cos(0.5\pi n)$ is $x_e[n] = \cos(0.5\pi n)$.
1.1 (a) The range of values that can be represented by 12-bit signed binary numbers is -2048 to 2047.
$$y[n] = x[2n]$$
$$h[n] = 0.5^n u[n]$$