Texas Instruments PLUS TI-89 - Manual (Page 84)

Chapter 3: Symbolic Manipulation 67
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 67 of 24
To type the “with” operator ( | ), press:
TI . 89: Í
TI . 92 Plus: 2 Í
For every occurrence of a
specified variable, you can
substitute a numeric value or an
expression.
To substitute for multiple
variables at the same time, use
the Boolean
and operator.
For every occurrence of a simple
expression, you can substitute a
variable, numeric value, or
another expression.
By replacing a commonly used
(or long) term, you can display
results in a more compact form.
You can substitute complex
values just as you would for other
values.
All undefined variables are treated as real numbers in symbolic
calculations. To perform complex symbolic analysis, you must define
a complex variable. For example:
x+y i! z
Then you can use z as a complex variable. You can also use z_. For
more information see the _ (underscore) topic in Appendix A.
Substituting Values and Setting Constraints
The “with” operator ( | ) lets you temporarily substitute values
into an expression or specify domain constraints.
Typing the “With”
Operator
Substituting for a
Variable
Substituting for a
Simple Expression
Note: acos(x) is different
from a*cos(x).
Substituting
Complex Values
Note: For an overview of
complex numbers, refer to
Appendix B.
Tip: To get the complex i ,
press 2 ) . Do not simply
type the letter i on the
keyboard.
First derivative of x ìò at x = 5
Substituting s for sin(x) shows that
the expression is a polynomial in
terms of sin(x).