Chain rule
In calculus, the chain rule is a formula that expresses the derivative of the composition of two differentiable functions f and g in terms of the derivatives of f and g. More precisely, if
h
=
f
∘
g
{\displaystyle h=f\circ g}
is the function such that
h
(
x
)
=
f
(
g
(
x
)
)
{\displaystyle h(x)=f(g(x))}
for every x, then the chain rule is, in Lagrange's notation,
https://en.wikipedia.org/wiki/Chain_rule
