\(\mathop {\lim }\limits_{x \to {3^ - }} \dfrac{1}{{x - 3}}\) bằng:

* Hướng dẫn giải

Ta có \(\left\{ \begin{array}{l}\mathop {\lim }\limits_{x \to {3^ - }} 1 = 1\\\mathop {\lim }\limits_{x \to {3^ - }} \left( {x - 3} \right) = 0,\,\,x \to {3^ - } \Rightarrow x - 3 < 0\end{array} \right. \Rightarrow \mathop {\lim }\limits_{x \to {3^ - }} \dfrac{1}{{x - 3}} =  - \infty \).

Chọn B.