HP HP-28S - Using FORM

Isolate x. The command ISOL appears in the second row of the AL-
GEBRA
menu as well as the SOLVE menu.
I NEXT I ISOL
The expression returned represents a symbolic solution of the equa-
tion for x-that is, the equation
2(a + x) = 3(b - x) + c
is satisfied when x = (3b + c - 2a)j5.
Using FORM
If there are multiple occurrences of x, and if any occurrence has a
symbolic coefficient,
the command COLCT won't combine the coef-
ficients. The next example isolates x in the equation
a(x + b) + 2x = c,
where x occurs more than once and has a symbolic coefficient a. The
strategy is to expand the equation, use FORM to collect coefficients of
x, and then isolate x.
Put the equation on the stack.
~ A 0[0 X eB B .[DeB 2 0 X 0
c I ENTER I
Expand the equation.
I NEXT I EXPAH
Now use FORM to collect the coefficients of x.
FORM
112 9: Symbolic Solutions