HP 50g Graphing Calculator - Manual (Page 790)

Page 27-8
Meanings of Menu Labels
Defining a set of equations
When you design a set of equations, you should do it with an understanding of
how the Multiple-Equation Solver uses the equations to solve problems.
The Multiple-Equation Solver uses the same process you’d use to solve for an
unknown variable (assuming that you were not allowed to create additional
variables). You’d look through the set of equations for one that has only one
variable that you didn’t know. You’d then use the root-finder to find its value.
Then you would do this again until you’ve found the variable you want.
You should choose your equations to allow likely unknown variables to occur
individually in equations. You must avoid having two or more unknown
variables in all equations. You can also specify equations in an order that’s best
for your problems.
Label Meaning
!!!!!!!!!X0!!!!!!!!!
Value x0 is not defined by you and not used in the last solution.
It can change with the next solution.
!!!!!!!X0!!лллл!!!
Value x0 is not defined by you, but it was found in the last
solution. It can change in the next solution.
$$X0$$
Value x0 is defined by you and not used in the last solution. It
cannot change in the next solution (unless you solve only for this
variable).
$#X0#qqqq!
Value x0 is defined by you and used in the last solution. It
cannot change in the next solution (unless you solve only for this
variable).