Texas Instruments TI-85 User Manual
Page 10
B-10
TI-85/TI-86 Graphing Calculators
Copyright © Houghton Mifflin Company. All rights reserved.
Press
ENTER
to display the output and see the point
marked on the graph of the function.
Repeat this process to find the outputs when x = 7 and
x = 10.
To evaluate an output from the home screen:
First, press
EXIT
until you are on the home screen.
Store the input value, say 5, in
x
by with
5
STO
‹
x-
VAR
ENTER
.
Next, type the location in the
y(x)=
list in which the
function is stored with
2nd
ALPHA
0
(
y
)
1
. Note
that the second function key is pressed before typing
the letter
y
in order to type lower-case
y
.
Warning:
The
TI-85
and the TI-86 distinguish between lower-case and upper-case
variable names. Locations in which equations are stored in the graphing
list are always referred to with lower-case letters.
If you had not pressed
2nd
before
ALPHA
and
therefore entered
Y1
, you would be using another
variable stored in the calculator's memory. (Your
values may be different from the ones shown to the
right or you may get an
UNDEFINED
error.)
Note that on the TI-85,
y1(5)
multiplies
y1
by 5.
To evaluate another output, simply store the input value
in
x
, type
y1
and press
ENTER
.
Evaluate
y1
= 1000(1 + 0.05^
x
) at
x
= 7 and
x
= 10.
¥ The values obtained by either of these evaluation processes are actual output values of
the equation, not estimated values such as those generally obtained by tracing.
TI-86: Evaluating outputs from the home screen
While the evaluation process
indicated above works on the TI-86, advances in the TI-86 technology give you a way to
evaluate functions from the home screen using fewer keystrokes than for the TI-85.
Type
2nd
ALPHA
0
(
y
)
1
and then press
(
5
)
. Press
ENTER
.
On the TI-86, typing a value in parentheses following
a function evaluates the function at that input value.