Tính \(\mathop {\lim }\limits_{x \to 2} \dfrac{{{x^3} - 6{x^2} + 11x - 6}}{{{x^2} - 4}}\)bằng?

Câu hỏi :

Tính \(\mathop {\lim }\limits_{x \to 2} \dfrac{{{x^3} - 6{x^2} + 11x - 6}}{{{x^2} - 4}}\) bằng?

A. \(\dfrac{1}{4}.\)

B. \(\dfrac{1}{3}.\)

C. \( - \dfrac{1}{4}.\)

D. \( - \dfrac{1}{3}.\)

* Đáp án

C

* Hướng dẫn giải

\(\mathop {\lim }\limits_{x \to 2} \dfrac{{{x^3} - 6{x^2} + 11x - 6}}{{{x^2} - 4}} = \mathop {\lim }\limits_{x \to 2} \dfrac{{\left( {x - 1} \right)\left( {x - 2} \right)\left( {x - 3} \right)}}{{\left( {x - 2} \right)\left( {x + 2} \right)}} = \mathop {\lim }\limits_{x \to 2} \dfrac{{\left( {x - 1} \right)\left( {x - 3} \right)}}{{\left( {x + 2} \right)}} = \dfrac{{ - 1}}{4}\)

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