Giá trị của giới hạn

\[\mathop {\lim }\limits_{x \to - \infty } \left( {x - {x^3} + 1} \right) = \mathop {\lim }\limits_{x \to - \infty } {x^3}\left( {\frac{1}{{{x^2}}} - 1 + \frac{1}{{{x^3}}}} \right) = + \infty \]

\(\left\{ {\begin{array}{*{20}{c}}{\mathop {lim}\limits_{x \to - \infty } {x^3} = - \infty }\\{\mathop {lim}\limits_{x \to - \infty } (\frac{1}{{{x^2}}} - 1 + {{\frac{1}{{x3}}}^{}}) = - 1 < 0}\end{array}} \right.\)