quadineq.82p - From the Spring 1996 issue of Eightysomething!


Graphing Quadratic Inequalities
Program by Krissy Couture
Edited by Nils Ahbel

Krissy Couture is a sophomore at Bellows Free Academy in St. Albans,
Vermont.  At the beginning of last year her mother won a TI-82 in a drawing
at her schools Mathematics Department Calculator Open House.  Since then,
Krissy has become very proficient at programming the TI-82.  Her teacher,
Mr. Berthiaume, challenged her to create a program to graph quadratic
inequalities.  Her results are given below.

The program allows you to graph not only Y=AX^2+BX+C, but also Y>, Y , Y<,
and Y  AX^2+BX+C.  For inequalities, the graph is displayed in two steps.
First, the boundary of the graph of the inequality is displayed, dotted <
and >, and solid for >= and <=.  Second , the shaded region is filled in.
It then displays the axis of symmetry, the coordinates of the vertex, the
x-intercept, and the y-intercept(s) if they exist.  Display screens for
Y>2X^2-3X-9 are given below.

...
Thanks to Laura Gonyeau for submitting the program!

