how can i plot these dsp signals?

i tried plotting these signals and this is the code i've used but it's not quite right

n=[1:50];
S=2*(n.*(0.9).^n)
plot(S);
x=rand(1,50);
plot(x);
q=S + x;
plot(S,x);

please help me

Answer 1

[Rahul Kalampattel]

I think what you have is correct, except in the last command you should be plotting q rather than S and x. Also if you want all the lines to appear on the same figure, you need to plot them together or hold the figure.

figure 
hold on

n=1:50; 
x=rand(size(n));
plot(x,'r'); 

S=2*(n.*(0.9).^n);
plot(S,'b--') 

q = S+x;
plot(q,'r-.');

legend('x', 'S', 'q');