Tính lim x → 1 + (− 2 x + 1)/( x − 1) bằng

10/22

Tính \(\mathop {\lim }\limits_{x \to {1^ + }} \frac{{ - 2x + 1}}{{x - 1}}\) bằng

\( + \infty \).

\( - \infty \).

\(\frac{2}{3}\).

\(\frac{1}{3}\).

Giải thích

Chọn B

\(\left\{ \begin{array}{l}\mathop {\lim }\limits_{x \to {1^ + }} \left( { - 2x + 1} \right) = - 1\\\mathop {\lim }\limits_{x \to {1^ + }} \left( {x - 1} \right) = 0\\x \to {1^ + } \Rightarrow x - 1 > 0\end{array} \right. \Rightarrow \mathop {\lim }\limits_{x \to {1^ + }} \frac{{ - 2x + 1}}{{x - 1}} = - \infty \)