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

 Example: f (x)=x2-1

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

Enter the antiderivative F (x) (so that F '(x)=f (x)) in the text input field marked "F(x)=".

 Example: F (x)=x3/3-x

Enter the endpoints of the interval [a,b] for the definite integral in the text input fields marked "a=" and "b=", and click the "Graph" button to refresh.

 Example: [a,b]=[0,2]

To erase the graph and all input fields, click the "Clear" button.

   f (x)=x2-1
   F (x)=x3/3-x

   f (x)=ex
   F (x)=ex

   f (x) = cos x
   F (x) = sin x

Other Notes
The graph shows f(x), with the area under the curve on the interval [a,b] shaded so that positive areas are blue and negative areas are red. A label under the graph shows the net area under the graph.

In the "Polynomial" example above, part of the shaded area is above the x-axis (in blue) and part below it (in red). The area above the axis is a bit larger than the area below it, giving a positive value for net area (blue area minus red area).