n1=0:10;
Xn1=0.8*exp(n1).*(heaviside(n1)-heaviside(n1-5));
n2=0:4;
Xn2=ones(1,5);
nys=n1(1)+n2(1);
nyf=n1(end)+n2(end);
y=conv(Xn1,Xn2);?
ny=[nys:nyf];
figure(1)
stem(n1,Xn1);
figure(2);
stem(n2,Xn2);
figure(3)
stem(y,ny);