30) $$(1.2n + 4y^2)(4y^2 - 1.2n) = (4y^2 + 1.2n)(4y^2 - 1.2n) = (4y^2)^2 - (1.2n)^2 = 16y^4 - 1.44n^2$$
Ответ: $$16y^4 - 1.44n^2$$