Tính \(\mathop {\lim }\limits_{x \to {1^ + }} \frac{{\sqrt {{x^2} - x + 3} }}{{2\left| x \right| - 1}}\) bằng:

Câu hỏi :

Tính \(\mathop {\lim }\limits_{x \to {1^ + }} \frac{{\sqrt {{x^2} - x + 3} }}{{2\left| x \right| - 1}}\) bằng:

A. 3

B. \(\frac{1}{2}\)

C. 1

D. \( + \infty \)

* Đáp án

A

* Hướng dẫn giải

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

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