Why does [math]\frac{\frac{d}{dx} x}{x} = \frac{1}{x}[/math]?
Is [math]\frac{d}{dx}  e^{-x} = e^{-x} [/math]or [math] -e^{-x} [/math]?
מדוע [math]\frac{\frac{d}{dx} x}{x} = \frac{1}{x}[/math]?
האם [math]\frac{d}{dx} e^{-x} = e^{-x} [/math] או [math] -e^{-x} [/math]?