Texas Instruments TI-89 Guide Book

74 Chapter 3: Symbolic Manipulation
03SYMBOL.DOC TI-89/TI-92 Plus: Symbolic Manipulation (English) Susan Gullord Revised: 02/23/01 10:52 AM Printed: 02/23/01 2:12 PM Page 74 of 24
Use the
zeros
(
„
4
) function.
zeros
(expression, var)
Use the expression
x
ù
sin(x) + cos(x)
.
Find the zeros with respect to
x
in the interval
0

x
and
x

3
.
Use the
propFrac
(
„
7
) and
comDenom
(
„
6
) functions.
propFrac
(rational expression [,var])
comDenom
(expression [,var])
Find a proper fraction for the
expression
(x
4
ì
2x
ñ
+ x) / (2x
ñ
+ x + 4)
.
Then transform the answer into
a ratio of a fully expanded
numerator and a fully expanded
denominator.
Notice that
propFrac
and
comDenom
perform opposite
operations.
In this example:
¦
31 x + 60
8
is the remainder of
x
4
ì
2x
ñ
+x
divided by
2x
ñ
+x+4
.
¦
x
ñ
2
ì
x
4
ì
15/8
is the quotient.
Finding the Zeros of
an Expression
Tip: For
‚
or

, type
¥ Ã
or
¥ Â
.You can also use
2I
8
or
2¿
2
to
select them from a menu.
Finding Proper
Fractions and
Common
Denominators
Note: You can use
comDenom
with an
expression, list, or matrix.
for proper fractions with respect
to a variable
Use the “with”
operator to specify
the interval.
for common denominators that collect
similar powers of this variable
for common denominators that collect
similar powers of this variable
If you do this example on your
TI
-
89 / TI
-
92 Plus, the
propFrac
function scrolls off the top of the
screen.

Texas Instruments TI-89 Specifications

General

Display size (HxV)	100 x 160 mm
Memory type	639K FLASH ROM, 188K bytes RAM
Compatible operating systems	Operating System 2.09
Battery type	AAA