Nếu \(\mathop {\lim }\limits_{} {\mkern 1mu} {u_n} = 9\) thì \(\mathop {\lim }\limits_{} {\mkern 1mu} \frac{{2018}}{{\sqrt {{u_n} + 7} }}\)&nb

Câu hỏi :

Nếu \(\mathop {\lim }\limits_{} {\mkern 1mu} {u_n} = 9\) thì \(\mathop {\lim }\limits_{} {\mkern 1mu} \frac{{2018}}{{\sqrt {{u_n} + 7} }}\) bằng

A. 504,5

B. 126,125.

C. 2018

D. 224,2

* Đáp án

A

* Hướng dẫn giải

\(\mathop {\lim }\limits_{} {\mkern 1mu} {u_n} = 9 \Rightarrow \mathop {\lim }\limits_{} {\mkern 1mu} \frac{{2018}}{{\sqrt {{u_n} + 7} }} = \mathop {\lim }\limits_{} {\mkern 1mu} \frac{{2018}}{{\sqrt {9 + 7} }} = 504,5\)

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