$\displaystyle M(a)=\frac{\lim}{\Delta x\rightarrow 0}\frac{a^\Delta ^x-1}{\Delta x}$

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$\displaystyle M(a)=\frac{d}{dx}a^x...at...x=0$

"2. Geometrically, M(a) is the slope of the graph y = ax at x = 0."

My question is what about the other points other than 0 where a^x is equal to 1? Right now I think that the slope at 2 is M(a)a^x however the documents seem to me right now to be saying that M(a) only is the slope at the other points such as 2. I'm trying to clear this up.

Thanks in advance...