**Learning objectives**

- Interpret and use partial derivatives as multipliers with units
- Use the master equation for and small and
- Make numerical approximations of partial derivatives
- Use a partial derivative in applied contexts (local linear approximation)
- Consult the main points of the lesson

**Before class**

- Read Hughes-Hallett 9.3
- Ponder problems 9.3.1, 2, 6, 10, 12.

**In class**

- Approximating and using partial derivatives: work on problems.