Giới hạn lim x đến -1 x^2+x/ ( x+1)^3  bằng

Đáp án đúng là: B

 $\underset{x\to -1}{\lim }\frac{x^2+x}{{\left(x+1\right)}^3}=\underset{x\to -1}{\lim }\frac{x\left(x+1\right)}{{\left(x+1\right)}^3}=\underset{x\to -1}{\lim }\frac{x}{{\left(x+1\right)}^2}=-\infty$.

Vì  $\left\{\begin{array}{c}\underset{x\to -1}{\lim }x=-1<0\\ \underset{x\to -1}{\lim }{\left(x+1\right)}^2=0\\ x\to -1\Rightarrow {\left(x+1\right)}^2>0\end{array}\right.$.