Texas Instruments -84 Plus, Manual Book

Page: 469 / 696

Chapter 17: Activities 466
Box with Lid Box with Lid Box with Lid Box with Lid
Defining a Function
Defining a Function Defining a Function
Defining a Function
Take a 20 cm × 25 cm. sheet of paper and cut X × X squares from two corners. Cut
X × 12½ cm rectangles from the other two corners as shown in the diagram below. Fold
the paper into a box with a lid. What value of X would give your box the maximum
volume V? Use the table and graphs to determine the solution.
1. Press
o
to display the
Y=
editor, which
is where you define functions for tables
and graphing.
Begin by defining a function that describes
the volume of the box.
From the diagram:
2X + A = 20
2X + 2B = 25
V = A
…
B
…
X
X
A
X B
X B
20
25