(9x-2)(9x-2), we can do it sequentially, by just multiplying one term times the other, and then the other term times the others. So in essence (a+b)(c+d) can be done sequentially by a(c) + a(d) + b(c) + b(d), and polynomial multiplication is done in the same way, FOIL is just a quick shortcut, that only works on binomials, sequentially works on any multiplication.
![\bf (9x-2)(9x-2)\implies \stackrel{9x(9x)}{81x^2}+\stackrel{9x(-2)}{(-18x)}+\stackrel{-2(9x)}{(-18x)}+\stackrel{-2(-2)}{(+4)} \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ ~\hfill 81x^2-36x+4~\hfill](https://img.qammunity.org/2019/formulas/mathematics/middle-school/qevhh6mlarfjbcezsn900cy1z4tc5cz69w.png)