Exercício Resolvido de Limites
f)
\( \displaystyle \lim_{h\rightarrow 0}\;{\frac{(x+h)^{3}-x^{3}}{h}} \)
Desenvolvendo o
Produto Notável
\( (a+b)^{3}=a^{3}+3a^{2}b+3\mathit{ab}^{2}+b^{3} \)
\[
\begin{align}
\lim_{h\rightarrow 0}\;{\frac{(x+h)^{3}-x^{3}}{h}} &=\lim_{h\rightarrow 0}\;{\frac{x^{3}+3x^{2}h+3 xh^{2}+h^{3}-x^{3}}{h}}=\\[5pt]
&=\lim_{h\rightarrow 0}\;{\cancel{h}\left(3x^{2}+3 xh+h^{2}\right)\frac{1}{\cancel{h}}}=\\[5pt]
&=\lim_{h\rightarrow 0}\;{\left(3x^{2}+3x.0+0^{2}\right)}=3x^{2}
\end{align}
\]
\[ \bbox[#FFCCCC,10px]
{\lim_{h\rightarrow 0}\;{\frac{(x+h)^{3}-x^{3}}{h}}=3x^{2}}
\]