TI89-28
Chapt er 1
Copyright © Houghton Mifflin Company. All rights reserved.
Press
ENTER .
The message on the
right appears on your screen. Press
ENTER
again. If you have not entered
the data in the correct location, press
2
[no]
. If you are ready to continue, press
1[yes]
or
ENTER .
Press
F1 [Choice?] 1 [first differences].
(Options 2 and 3 are used in the next
chapter of this Guide.)
The first differences are displayed.
Press
F1 [Choice?] 4 [Quit program].
To return to the home screen, press
F5 [PrgmIO]
or
HOME .
If you need to scroll the list to see the
rest of the first differences or recall
them, enter
d1
in the entry line.
•
The first differences are constant at 541, so a linear function gives a perfect fit to these tax
data.
Note: Program
DIFF
should not be used for data with input values (
c1
)thatarenot evenly
spaced. First differences give no information about a possible linear fit to data with inputs that
are not the same distance apart. If you run program
DIFF
with input data that are not evenly
spaced, the message
INPUT VALUES NOT EVENLY SPACED
appears and the program stops.
1.5.5 SCATTER PLOT SETUP The first time that you draw a graph of data, you need to set the
TI-89 to draw the type of graph you want to see. Once you do this, you never need to do this
set up again (unless for some reason the settings are changed). If you always put input data in
list
c1
and output data in list
c2
, you can turn the scatter plots off and on from the
Y=
screen
rather than the
Plot Setup
screen after you perform this initial setup.
Access the data with
APPS 6 [Data/Matrix Editor]
and choose
1
[Current].
Press
F2 [Plot Setup].
(Your screen may not look
exactly like this one.)
On the
Plot Setup
screen, have
Plot 1
highlighted and press
F1
[Define].
Choose the options shown on the right. (You can
choose any of the 5 available marks.) Type in
c1
for
x
and
c2
for
y
.
Press
ENTER
to save the settings. Note that
Plot 1
is turned on
because there is a check mark to the left of the name. Press
ENTER
to return to the data lists.
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