\hsize 0pt
\vsize 0pt
\nopagenumbers
\overfullrule 0pt
\noindent
$$
\eqalign {
y(n) = &\alpha x(n) + \beta(1 + \alpha)x(n - 1) + x(n - 2)
\cr
- &\beta(1 + \alpha)y(n - 1)  - \alpha y(n - 2)
}
$$
\bye