问题
以下关于【函数左导数】的描述中正确的是哪项？选项
[A]. $\lim_{\Delta x \rightarrow 0^{\color{Red}{-}}}$ $\frac{f(x_{0} + \Delta x) – f(x_{0})}{\Delta x}$[B]. $\lim_{\Delta x \rightarrow 0^{\color{Red}{+}}}$ $\frac{f(x_{0} + \Delta x) + f(x_{0})}{\Delta x}$
[C]. $\lim_{\Delta x \rightarrow 0^{\color{Red}{-}}}$ $\frac{f(x_{0} + \Delta x) + f(x_{0})}{\Delta x}$
[D]. $\lim_{\Delta x \rightarrow 0^{\color{Red}{+}}}$ $\frac{f(x_{0} + \Delta x) – f(x_{0})}{\Delta x}$
$f_{\color{Red}{-}}^{‘}(x_{0})$ $=$ $\lim_{\Delta x \rightarrow 0^{\color{Red}{-}}}$ $\frac{f(x_{0} + \Delta x) – f(x_{0})}{\Delta x}$