Tính lim x → − vô cực ( căn bậc ba của x^3 + 1 + x − 1 ) bằng?

\[\mathop {\lim }\limits_{x \to - \infty } \left( {\sqrt[3]{{{x^3} + 1}} + x - 1} \right) = \mathop {\lim }\limits_{x \to - \infty } \left( {x\sqrt[3]{{1 + \frac{1}{{{x^3}}}}} + x - 1} \right)\]

\[ = \mathop {\lim }\limits_{x \to - \infty } \left[ {x\left( {\sqrt[3]{{1 + \frac{1}{{{x^3}}}}} + 1 - \frac{1}{x}} \right)} \right] = - \infty \]