TI89-4
Chapt er 1
Copyright © Houghton Mifflin Company. All rights reserved.
The TI-89 can switch to scientific notation when the number is too
large for the display area in a table or graph. The TI-89’s symbol for
“times 10
−
6
”is
E
−
6
.So,
1.4675
E
−
6
means 1.4675
*
10
−
6
,whichis
scientific notation for 0.0000014675. Enter
“
E
”
by pressing
EE .
The result
1.5
E
28
means 15,000,000,000,000,000,000,000,000,000 =
1.5(10
28
). In the history area, an arrowhead (
) that points to the
right at the end of a number means that the number or expression
continues. Highlight the number or expression and press
►
to
scroll and see the rest of it. Press
▼
to return to the entry line.
4. STORI NG VALUES It often is beneficial to store numbers or expressions for later recall. To
store a number, type the number, press
STO
alpha
, type the letter(s) corresponding to the stor-
age location, and then press
ENTER .
Join several short commands with a colon between the
statements. Note that when you join statements with a colon by pressing
2nd 4
(
:
)
, only the value
of the last statement is shown as a result.
Store 5 in a and 3 in b,andthencalculate4a–2b.
To recall a stored value, press
alpha
, type the letter in which the
expression or value is stored, and then press
ENTER .
•
Storage location names on the TI-89 can be from one to eight characters long and use letters
and numbers, but they must begin with a letter. You cannot name what you are storing with
thesamenamethattheTI-89alreadyusesforabuilt-invariable(suchas
LOG
or
ans
).
•
Whatever you store in a particular memory location stays there until it is replaced by some-
thing else either by you or by executing a program containing that name. It is advisable to
use single-letter names so that the values will be cleared when you begin with
NewProb
.
NOTE: The TI-89 allows you to enter upper and lower case letters, but it does not distinguish
between them. For instance,
VOL, Vol, VOl, vol, voL
, and so forth all name the same variable. To
type a lower-case letter, press
alpha
before typing a letter key (note that a lower-case
a
appears
under the entry line). To type an uppercase-letter, press
alpha
(note that an upper-case
A
appears under the entry line) before typing the key corresponding to the letter.
If a variable is undefined (i.e., you have not stored a value in it), it
is treated as an algebraic symbol. If a variable is defined, its value
replaces the variable when you enter an expression containing that
variable. It is best, as we see in later chapters, to leave the names x
and y as undefined variables.
WARNING: You must be very careful when entering expressions containing variables. In the
next-to-last expression shown on the screen above, the TI-89 assumes “ax” refers to the name of a
single undefined variable. To tell the calculator that you want to multiply the variable a by the
variable x, you must use
between the letters. Also, because 5 has been stored to a, the TI-89
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