## NEKG33 Mathematical methods for economists

## Chapter 9 : Day 09: Partial derivatives

### By Lund University

Ordinary derivatives are for newbies. Today we move on from functions of a single variable to functions of several variables and do partial derivatives.

## Functions of two variables

In this section we investigate functions z = f(x,y).

#### Problem: Evaluate a function of two variables

#### Problem: Evaluate a function of two variables

## Partial derivatives

For a function of two variables, we can define two derivatives, one for each variable. Such derivatives are called partial derivatives. Similarly, we get 4 second order partial derivatives.

#### Partial derivatives, rough introduction

## Partial derivatives: Problems

Exercises on partial derivatives.