| 3 | | ||<bgcolor=#fff,#1f2023><table width=100%><tablebordercolor=#fff,#1f2023><:> [math(\begin{aligned}f'(x)&=(\overbrace{x+x+ \cdots +x}^{x\;\rm{times}})'\\&= \displaystyle\lim_{h \to \ 0} \frac {\{\overbrace{(x+h)+(x+h)+ \cdots +(x+h)}^{(x+h)\;\rm{times}}\} - (\overbrace{x+x+ \cdots +x}^{x\;\rm{times}})}{h}\\&= \displaystyle\lim_{h \to \ 0} \frac {(\overbrace{h+h+ \cdots +h)}^{x\;\rm{times}} + \{\overbrace{(x+h)+(x+h)+ \cdots +(x+h)}^{h\;\rm{times}}\}}{h}\\&=x +\displaystyle\lim_{h \to \ 0} \frac{(xh+h^2)}{h}\\&=x+x=2x\end{aligned})] ||
|
|---|