Drugi

syms a, t, h, g
g(t,a) = (36-6*a) * exp(-6*t) + (6*a -18) * exp(-3*t);
h(t,a) = (a-6*a) * exp(-6*t) + (2*a - 6) * exp(-3*t);

% a = 6
G = tf(18*[1 6],[1 9 18]);
step(G)

% a = 3
G = tf(18*[1 3],[1 9 18]);
step(G)

% a = 1
G = tf(18*[1 1],[1 9 18]);
step(G)

% a = -1
G = tf(18*[1 -1],[1 9 18]);
step(G)
pzmap(G)