Derivative of Identity Function

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Note that this can be more compactly written $D_x \left({x}\right) = 1$.

Using Leibniz's notation for derivatives $\left (\dfrac{\mathrm dy}{\mathrm dx}\right )$ this theorem can be stated as


 * $\displaystyle \frac{\mathrm dx}{\mathrm dx} = 1$

Which is not to say that derivatives are fractions, but the theorem is quite elegant this way.