Factorise:

We have:

$121 a^{2}-88 a b+16 b^{2}=(11 a)^{2}-2 \times 11 a \times 4 b+(4 b)^{2}$

$=(11 a-4 b)^{2}$

$\therefore 121 a^{2}-88 a b+16 b^{2}=(11 a-4 b)^{2}$