a) lim x->-3 (4x^2 + 11x - 3) / (x^2 + 2x - 3) , B) lim x->0 (sin 3x - sin 5x) / (sin 4x + sin x) , b) lim x->∞ (4 - 5x^2 - 3x^3) / (2x^3 + 6x + 7) , r) lim x->∞ ((2 - 6x) / (3 - 6x))^(4 - 6x)