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Product and chain rule

When a function is built up from several functions, we need special rules to differentiate it. The product rule applies to a product of two functions, and the chain rule to a function inside another function.

(fg)′=f′g+fg′(fg)' = f'g + fg'the product rule
(fg)′=f′g−fg′g2\left(\frac{f}{g}\right)' = \frac{f'g - fg'}{g^2}the quotient rule
(f(g(x)))′=f′(g(x))⋅g′(x)\big(f(g(x))\big)' = f'(g(x))\cdot g'(x)the chain rule

Symbols

f, gf,\ gfunctions of x

Example

f(x)=x2exf(x)=x^2e^x: f′(x)=2xex+x2exf'(x) = 2xe^x + x^2e^x (product rule), so f′(0)=0f'(0)=0.

In the quotient rule the minus sign and g2g^2 in the denominator matter - don't swap the terms.
Practise differentiation for free →

Standard derivatives →

Part of Calculus: Differentiation.