Logarithmic differentiation
In calculus, logarithmic differentiation or differentiation by taking logarithms is a method used to differentiate functions by employing the logarithmic derivative of a function f, ( ln f ) ′ = f ′ f ⟹ f ′ = f ⋅ ( ln f ) ′ . {\displaystyle (\ln f)'={\frac {f'}{f}}\quad \implies \quad f'=f\cdot (\ln f)'.} The technique is often performed in cases where it is easier to differentiate the logarithm of a function rather than the function itself.
Source: Wikipedia — Logarithmic differentiation (CC BY-SA 4.0)