Solve aplet 7-5
Use an initial guess
You can usually obtain a faster and more accurate 
solution if you supply an estimated value for the unknown 
variable before pressing  . Solve starts looking for 
a solution at the initial guess. 
Before plotting, make sure the unknown variable is 
highlighted in the numeric view. Plot the equation to help 
you select an initial guess when you don’t know the range 
in which to look for the solution. See “Plotting to find 
guesses” on page 7-7 for further information.
HINT
An initial guess is especially important in the case of a 
curve that could have more than one solution. In this case, 
only the solution closest to the initial guess is returned.
Number format You can change the number format for the Solve aplet in 
the Numeric Setup view. The options are the same as in 
HOME MODES: Standard, Fixed, Scientific, and 
Engineering. For the latter three, you also specify how 
many digits of accuracy you want. See “Mode settings” 
on page 1-10 for more information.
You might find it handy to set a different number format 
for the Solve aplet if, for example, you define equations 
to solve for the value of money. A number format of 
Fixed 2 would be appropriate in this case.
Clears highlighted variable to zero or 
deletes current character in edit line, 
if edit line is active.
CLEAR Resets all variable values to zero or 
clears the edit line, if cursor is in edit 
line.
Key Meaning (Continued)
HP 39gs English.book  Page 5  Wednesday, December 7, 2005  11:24 PM