1. **State the problem:** Differentiate the function $f(x) = 2x$ with respect to $x$. 2. **Recall the differentiation rule:** The derivative of $x$ with respect to $x$ is 1, and the derivative of a constant multiplied by a function is the constant multiplied by the derivative of the function. 3. **Apply the rule:** $$\frac{d}{dx}(2x) = 2 \cdot \frac{d}{dx}(x)$$ 4. **Calculate the derivative:** $$2 \cdot 1 = 2$$ 5. **Final answer:** The derivative of $2x$ is $2$.