Найти пределы a) lim (x → ∞) (3x^3 + 4) / (x + 2)^3 b) lim (x → 1) (x^2 + 2x - 3) / √(x - 1) d) lim (x → ∞) (x^2 + 3)^2 / (x^2 + 1) b) lim (x → 1) (7x^2 - 8x + 1) / (13x^2 - 10x - 3) r) lim (x → 1) sin(x - 1) / (x^2 - 1)