2) $$(5a^2 + 4a + 3) - (2a^2 + 3a - 1) = 5a^2 + 4a + 3 - 2a^2 - 3a + 1 = (5a^2 - 2a^2) + (4a - 3a) + (3 + 1) = 3a^2 + a + 4$$
Ответ: $$3a^2 + a + 4$$