Exercício Resolvido de Limites
b)
\( \displaystyle \lim_{x\rightarrow 3}\;{\frac{x^{2}+3}{x^{2}-3}} \)
Colocando
x2 em evidência no numerador e no denominador
\[
\begin{align}
\lim_{x\rightarrow 3}\;{\frac{\cancel{x^{2}}\left(1+\dfrac{3}{x^{2}}\right)}{\cancel{x^{2}}\left(1-\dfrac{3}{x^{2}}\right)}} &=\lim_{x\rightarrow3}\;{\frac{\left(1+\dfrac{3}{3^{2}}\right)}{\left(1-\dfrac{3}{3^{2}}\right)}}=\lim_{x\rightarrow3}\;{\frac{\left(1+\dfrac{3}{9}\right)}{\left(1-\dfrac{3}{9}\right)}}=\\[5pt]
&=\lim_{x\rightarrow3}\;{\frac{\left(\dfrac{9+3}{\cancel{9}}\right)}{\left(\dfrac{9-3}{\cancel{9}}\right)}}=\lim_{x\rightarrow 3}\;{\frac{12}{6}}=2
\end{align}
\]
\[ \bbox[#FFCCCC,10px]
{\lim_{x\rightarrow 3}{\frac{x^{2}+3}{x^{2}-3}}=2}
\]