HP 39gs Master Manual page 203

POLYFORM(<expression>,<var_name>)
This is a very powerful and useful polynomial function. It allows
algebraic manipulation and expansion of an expression into a
polynomial. The expected parameters for the function are firstly the
expression to be expanded, and secondly the variable which is to be the
subject of the resulting polynomial. If the expression contains more than
one variable then any others are treated as constants.
(
Eg. 1 Expand
2 x − 3
Result: 8x − 52 x + 134x
5 4
The resulting polynomial is shown both as it appears in the
key. Once it appears in the
missing terms.
(
Eg. 2 Expand
3 a − 2 b
This function contains two variables,
separately.
The first expansion, treating
expression
POLYFORM((3A-2B)^4,A)
the view after pressing
of has been done, but the terms involving
A
The solution to this is to use
edit line, then move the cursor up to the partially evaluated expression that was the result of the previous
. Copy it into the edit line and add a comma, a
POLYFORM
now evaluate the terms involving
After pressing the for the second evaluation, the result is shown
ENTER
right (after pressing
) ( )
3 x −1 2
− 171 x + 108 x − 27
3 2
window, of course, it can be scrolled right and left to see the
)
4
and , which must be expanded
A B
as the variable, is done using the
A
. As you can see if you examine
, the expansion of the expression in terms
are not fully evaluated.
B
again. Use the
POLYFORM
.
B
).
view and as it appears after pressing the
HOME
menu to fetch the
MATH
and an end bracket. Pressing
B
203
function to the
POLYFORM
will
ENTER