[BigZcoder]

Consider the DT, LTI system with the z-domain transfer function H(z) = z/z^2 −2⋅(0.95)cos(π/6)z+(0.95)^2
Plot the magnitude and phase of the frequency response of the system.

Program the corresponding difference equation, and iterate to determine the responses to the inputs
x1(k) = cos(kπ /12)⋅us (k),
x2(k) = cos(kπ /6)⋅us (k),
x3(k) = cos(kπ /3)⋅us (k).

H = tf([1], [1 -1.645 .9025]);
bode(H)

this is all I have so far, which satisfies part A but I'm not sure how to incorporate the x(k)'s

[calvinthedestroyer]

I don't know but the wiki page has some examples about the LTI system.
LTI system theory

What does the DT stand for?

What class / technical area is this for?

[sepp2k]

When asking a question in a non-language specific forum, you should really specify which language you're asking about. Is it Matlab?