Tính các giới hạn sau: lim x suy ra -3 ((-x^2 + 2x + 15) / (x^2 + 4x + 3))

\(\mathop {\lim }\limits_{x \to - 3} \frac{{ - {x^2} + 2x + 15}}{{{x^2} + 4x + 3}}\)\( = \mathop {\lim }\limits_{x \to - 3} \frac{{\left( {5 - x} \right)\left( {x + 3} \right)}}{{\left( {x + 1} \right)\left( {x + 3} \right)}} = \mathop {\lim }\limits_{x \to - 3} \frac{{5 - x}}{{x + 1}} = - 4\).