Soit la fonction définie sur \( ]-\infty\,; {-3}[\cup ] {-3}\,; +\infty[ \) par \( \begin{aligned}  f(x)={\frac{x^2-4\,x-21}{x+3}} \end{aligned} \)

Calculez les limites ci-dessous

1. \( \begin{aligned} \lim\limits_{x \to \, +\infty} \left({\frac{x^2-4\,x-21}{x+3}}\right)= \end{aligned} \)

2. \( \begin{aligned} \lim\limits_{\substack{x \, \to \,{-3} \\ x \, > \, {-3}}} \left({\frac{x^2-4\,x-21}{x+3}}\right)= \end{aligned} \)

3. \( \begin{aligned} \lim\limits_{\substack{x \, \to \,{-3} \\ x \, < \, {-3}}} \left({\frac{x^2-4\,x-21}{x+3}}\right)= \end{aligned} \)

4. \( \begin{aligned} \lim\limits_{x \to \, -\infty} \left({\frac{x^2-4\,x-21}{x+3}}\right)= \end{aligned} \)