# Product Rule

• In calculus, the product rule is a formula used to find the derivatives of products of two or more functions. It may be stated thus: $(f\cdot g)'=f'\cdot g+f\cdot g' \,\!$ or in the Leibniz notation thus: $\dfrac{d}{dx}(u\cdot v)=u\cdot \dfrac{dv}{dx}+v\cdot \dfrac{du}{dx}$.
The derivative of the product of three functions is: $\dfrac{d}{dx}(u\cdot v \cdot w)=\dfrac{du}{dx} \cdot v \cdot \lt math\gt w$ + u \cdot \dfrac{dv}{dx} \cdot $w$ + u\cdot v\cdot \dfrac{dw}{dx}[/itex].