Operation Manual
6 Getting Started
8200GETS.DOC TI-82, Getting Started, English Bob Fedorisko Revised: 02/09/01 8:38 AM Printed:
02/09/01 12:35 PM Page 6 of 14
Defining a Function: Box with Lid
Take a 200×250 mm. sheet of paper and cut X-by-X squares from two corners and
X-by-125 mm. rectangles from the other two corners. Now fold the paper into a
box with lid. What X would give the maximum volume V of a box made in this
way? Use tables and graphs to determine the solution.
Begin by defining a function that describes the
v
olume of the box.
From the diagram: 2X + A = W
2X + 2B = L
V = A B X
Substituting: V = (W – 2X) (L
à
2 – X) X
W
X
X
A
BXB
L
1. Press
z
†
Í
to change the
MODE
back
to
Float
.
2. Press
y
ã
Quit
ä
‘
to return to the Home
screen and clear it.
3. Press
200
¿
ƒ
W
y
ã
:
ä
250
¿
ƒ
L
Í
to store the width and length of
the paper.
4. You define functions for tables and graphing on
the
Y=
edit screen. Press
o
to access this
screen.
5. Enter the function for volume as
Y
1
. Press
£
ƒ
W
¹
2
„
¤
£
ƒ
L
¥
2
¹
„
¤
„
Í
to define function
Y
1
in terms of
X
. (
„
lets you enter
X
quickly, without
pressing
ƒ
.)
The
=
sign is highlighted to show that
Y
1
is
selected.