Derivative/R/Product of n functions/Exercise

Let $D\subseteq ℝ$ be a subset and let

$f_i:D⟶ℝ,i=1,\dots ,n,$

be differentiable functions. Prove the formula

${(f_1\cdots f_n)}^{\prime }=\sum _{i=1}^n{f}_1\cdots f_{i-1}{f}_{i^{\prime }}{f}_{i+1}\cdots f_n.$

Create a solution