HP 39g Graphing Calculator - Manual (Page 94)

8, Use this equation to solve for another variable, such as
velocity. How fast must a body’s initial velocity be in
order for it to travel 50 m within 3 seconds? Assume the
same acceleration, 4 m/s^. Leave the last value ofV as an
initial euess.
3OEEE10B0
50 j ENTER I
HI
i SOLVE NUMERIC VIEWg
10.6666&66667
ENTER VRLUE OR PRESS SOLVE______
Using variables in equations
Home
variables
H I N T
You can use any of the real variable names, A to Z and 0. Do
not use variable names defined for other types, such as Ml (a
matrix variable).
All home variables (other than those for aplet settings, like
Xmin and Ytick) are global, which means they are shared
throughout the different aplets of the calculator. A value that
is assigned to a home variable anywhere remains with that
variable wherever its name is used.
Therefore, if you have defined a value for T (as in the above
example) in another aplet or even another Solve equation, that
value shows up in the Numeric view for this Solve equation.
When you then redefine the value for T in this Solve equation,
that value is applied to T in all other contexts (until it is
changed again).
This sharing allows you to work on the same problem in
different places (such as HOME and the Solve aplet) without
having to update the value everywhere whenever it is
recalculated.
As the Solve aplet uses any existing variable values, be sure
to check for existing variable values that may affect the solve
process. (You can use |
shift |C££/tfi to reset all values to zero
in the Solve aplet’s Numeric view if you wish.)
Aplet variables
Functions defined in other aplets can also be referenced in the
Solve aplet. For example, if, in the Function aplet, you define
FI (X) =X^+10, you can enter FI (X) = 5 0 in the Solve aplet
to solve the equation X^ + 10 = 50.
7-10 Solve aplet