28) $$(20u+1.2q)^2 = (20u)^2 + 2 \cdot 20u \cdot 1.2q + (1.2q)^2 = 400u^2 + 48uq + 1.44q^2 $$
Ответ: $$400u^2 + 48uq + 1.44q^2$$