First, press [MODE] and check that Graph....... is set to FUNCTION. Set the display to Full Screen.

The generic curve could be produced in a variety of ways. We chose y = 1 + x⁴ and took this as y1 in the Y= screen. In the GRAPH screen it was plotted with WINDOW settings as shown below:

Note that in the GRAPH screen, the axes were turned off by [F1] 9:Format...

The fixed point on the curve has coordinates (1,2). The movable point would have coordinates (p , 1+p⁴). The equation of the straight line passing through these two points was found with a little algebra. This line was used as graph y2, and the "with" operator [2nd] K was used to specify the required value of p, which we took to vary between 2 down to 1 in steps of 0.1 . For example:

The graphs of y1 and y2 shown above resulted in the graph below:

Note that the dotted line was produced by highlighting y2 in the Y= screen and pressing [F6] 2:DOT. The value of xres in the WINDOW screen determines the level of "dottiness".

The equation of graph y2 can easily be edited to vary the value of p which produces a new slide for the animated GIF.

Use the TI-GRAPHLINK to capture each screenshot and copy each image into a graphics software package to save as a .gif file. The red and black points to highlight the position of the two points were added in the graphics software package. Use these individual images with your chosen GIF Animation programme.