plot zero input response

I am trying to plot the zero input response

Here is the code i have so far

syms y
n=0:99;
a_1=3;
a_2=4;
x=(-1/5*y(-1)+4/5*y(-2))*(-1)^n+(16/5*y(-1)+16/5*y(-2))*(4)^n;
plot(0:99,x)  

Answer 1

[randerss simil]

%if true
  syms y
n=0:99;
a_1=3;
a_2=4;
x=(-1/5*y+4/5*y)*(-1).^n+(16/5*y+16/5*y)*(4).^n;
fplot(x,[-2,-1])

Use fplot