Texas Instruments TI-89 Voyage 200, User Manual

Page: 254 / 1008

Symbolic Manipulation 254
Note:
Enter
ln(x
†
y)
instead of
ln(xy)
; otherwise, xy is interpreted as a single variable
named xy.
Note:
For
‚
or

, press
8 Ã
or
8 Â
. You can also use
2 I
8
or
2 G
2
to
select them from a menu.
Using Substitutions vs. Defining a Variable Using Substitutions vs. Defining a Variable Using Substitutions vs. Defining a Variable Using Substitutions vs. Defining a Variable
However, substitution is preferable for most cases because the variable is defined only
for the current calculation and does not accidentally affect later calculations.
Because sin
L
1
(sin( q )) = q is not always valid, the
expression is not simplified.
With a constraint, the expression can be simplified.
In many cases, you can achieve the same
effect as a substitution by defining the
variable.
Substituting x=1 does not affect the next
calculation.