Tính \(\mathop {\lim }\limits_{x \to - \infty } ({x^2} + x - 1)\)

* Hướng dẫn giải

\(\mathop {\lim }\limits_{x \to - \infty } ({x^2} + x - 1) = \mathop {\lim }\limits_{x \to - \infty } {x^2}(1 + \dfrac{1}{x} - \dfrac{1}{{{x^2}}}) = + \infty\)