HP 39gs Graphing manual Analyse graph with FCN functions, Select Root

Analyse graph with FCN functions

9. Display the Plot view menu.

From the Plot view menu, you can use the functions on the FCN menu to find roots, intersections, slopes, and areas for a function defined in the Function aplet (and any Function-based aplets). The FCN functions act on the currently selected graph. See “FCN functions” on page 3-10 for further information.

To find a root of the quadratic function

To find the intersection of the two functions

10.Move the cursor to the graph of the quadratic

equation by pressing the or key. Then move the cursor so that it is near x = –1by pressing the

or key.

Select Root

The root value is displayed at the bottom of the screen.

Note: If there is more than one root (as in our example), the

coordinates of the root closest to the current cursor position are displayed.

11.Find the intersection of the two functions.

3-4 Function aplet