In calculus [Calculus], the chain rule is a formula that expresses the derivative [Derivative (math)] of the composition of two differentiable functions \(f\) and \(g\) in terms of the derivatives of \(f\) and \(g\). More precisely, if \(h=f\circ g\) is the function such that \(h(x)=f(g(x))\) for every \(x\), then the chain rule is, in Lagrange’s notation [Lagrange’s notation],

\(h'(x)=f'(g(x))g'(x)\).

or, equivalently,

\(h'=(f\circ g)'=(f'\circ g)\cdot g'\).

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