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

 Example: f (x)=x2

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

Enter a value for c.

 Example: c=1

This can be done either of two ways:

Enter a value for x.

 Example: x=2

This can be done either of two ways:

To erase the graph and all input fields, click the "Clear" button.
Examples
 Polynomial: f (x)=x2, c=1, x=2

 Exponential: f (x)=ex, c=0, x=1

 Trigonometric: f (x)=sin(x), c=0, x=1


Other Notes
The values of c and f (c) are indicated in the graph by orange lines, with the red point in the graph shown at the point (c,f (c)). The values of x and f (x) are indicated in the graph by blue lines. The table shows values of f (x) for x starting at the given value and approaching c -- in particular, the values x, c+(x-c)/2, c+(x-c)/4, etc. These values are indicated in the graph by green lines.