Ок Оксана 1) lim((x - 7x + 12/(x - 4x + 3)) = lim((x - 4)(x - 3)/(x - 3)(x - 1)) = -1/2 Ответ: -1/2 2) f(x) = tg⁴(x); f'(x) = 3*4*xtg(x)/cos(x) = 12xtg(x)/cos(x)