14.6 - Multivariable Chain Rule

Theorem

Let be a differentiable function of n variables.
Suppose are differentiable functions of m independent variables

Then for

Mnemonic

Ex:


Recall
is an implicit function of and


14.7 Optimization

Local Extreme Values

A function has a local extremum at if there exists a neighborhood such that

  • local maximum
  • local minimum

Critical Points

A point in the domain of is called a critical point if

  • does not exist or does not exist

Theorem

If has a local min/max at then is a critical point of