Texas Instruments TI-82 Manual page 2

Even if you had pressed ENTER, you may still edit the previous expression. Press 2nd and then ENTRY to recall
the last expression that was entered. Now you can change it. In fact, the TI-82 retains many prior entries in a "last
entry" storage area. Press 2nd ENTRY repeatedly until the previous line you want replaces the current line.
Technology Tip: When you need to evaluate a formula for different values of a variable, use the editing feature to
simplify the process. For example, suppose you want to find the balance in an investment account if there is now
$5000 in the account and interest is compounded annually at the rate of 8.5%. The formula for the balance is
( )
nt
P +
1 r , where P = principal, r = rate of interest (expressed as a decimal), n = number of times interest is
n
compounded each year, and t = number of years. In our example, this becomes 5000(1+.085)
keystrokes for finding the balance after t = 3, 5, and 10 years.
Then to find the balance from the same initial investment but after 5 years when the annual interest rate is 7.5%,
press these keys to change the last calculation above: 2nd ENTRY ◄ DEL ◄5◄◄◄◄◄7 ENTER.
2.1.3 Key Functions: Most keys on the TI-82 offer access to more than one function, just as the keys on a computer
keyboard can produce more than one letter ("g" and "G") or even quite different characters ("5" and "%"). The
primary function of a key is indicated on the key itself, and you access that function by a simple press on the key.
To access the second function indicated to the left above a key, first press 2nd (the cursor changes to a blinking ↑)
and then press the key. For example, to calculate
When you want to use a letter or other character printed to the right above a key, first press ALPHA (the cursor
changes to a blinking ) and then the key. For example, to use the letter K in a formula, press ALPHA K. If you
A
need several letters in a row, press 2nd A-LOCK, which is like C
all the letters you want. Remember to press ALPHA when you are finished and want to restore the keys to their
primary functions.
2.1.4 Order of Operations: The TI-82 performs calculations according to the standard algebraic rules. Working
outwards from inner parentheses, calculations are performed from left to right. Powers and roots are evaluated first,
followed by multiplications and divisions, and then additions and subtractions.
2
G T
RAPHING ECHNOLOGY
Years Keystrokes
5000 ( 1 + .085 ) ∧ 3 ENTER
3
2nd ENTRY ◄ 5 ENTER
5
2nd ENTRY ◄ 10 ENTER
10
Figure 2.3: Editing expressions
25 , press 2nd
Copyright © Houghton Mifflin Company. All rights reserved.
G : TI-82
UIDE
t
Balance
$6,386.45
$7,518.28
$11,304.92
25 ENTER.
L
on a computer keyboard, and then press
APS OCK
. Here are the