\(\lim (\sqrt {{n^2} - n + 1} - n)\) bằng
A. 0 | B. 1 | C. \( - \frac{1}{2}\) | D. |
\(\begin{array}{l}
\lim \left( {\sqrt {{n^2} - n + 1} - n} \right) = \lim \frac{{\left( {{n^2} - n + 1} \right) - {n^2}}}{{\sqrt {{n^2} - n + 1} + n}}\\
= \lim \frac{{ - n + 1}}{{\sqrt {{n^2} - n + 1} + n}} = \lim \frac{{ - 1 + \frac{1}{n}}}{{\sqrt {1 - \frac{1}{n} + \frac{1}{{{n^2}}}} + 1}} = - \frac{1}{2}
\end{array}\)
Chọn C.
-- Mod Toán 11