How to use
Enter a function f (x) in the text input field marked "f(x)=".

 Example: f (x) = x2

Click the "Graph" button (this button also refreshes the graph).

Select values for x1 and x2.

 Example: x1=0, x2=1

This can be done in either of two ways:

To erase the graph and all input fields (setting x1 and x2 to default values), click the "Clear" button.
 Parabola: f (x) = x2, x1=0, x2=1

 Exponential: f (x) = ex, x1=0, x2=1

 Cosine: f (x) = cos x, x1=0, x2=0.5

Other Notes
Labels under the text input fields display the values of f (x1), f (x2), and the slope of the secant line.