Calculus
Intermediate

Product Rule

Derivative of a product of two functions.

Formula

(fg)=fg+fg(fg)' = f'g + fg'

Variables

f, gFunctions

Example

d/dx (x²·sin x) = 2x·sin x + x²·cos x.

Did You Know?

The product rule is NOT just the product of the derivatives — a mistake Leibniz himself first made.