Objectives: In this tutorial, we define differentials and illustrate how differentials can be used to make approximations.

• to understand the symbolic and geometric interpretations of differentials;
• to use differentials to approximate values of functions.

Definition. Let y = f(x) be a differentiable function. The differential of x, dx, is an independent variable. The differential of y is defined as dy = f '(x) dx

• Discussion [Using Flash]

• Drill problems on using differentials to make approximations.