HP 48gII User Manual page 101

In RPN mode, enter the equation between apostrophes and activate command
STEQ. Thus, function STEQ can be used as a shortcut to store an expression
into variable EQ.
Press J to see the newly created EQ variable:
Then, enter the SOLVE environment and select Solve equation..., by using:
‚Ï@@OK@@. The corresponding screen will be shown as:
The equation we stored in variable EQ is already loaded in the Eq field in the
SOLVE EQUATION input form. Also, a field labeled x is provided. To solve
the equation all you need to do is highlight the field in front of X: by using
˜, and press @SOLVE@. The solution shown is X: 4.5006E-2:
This, however, is not the only possible solution for this equation. To obtain a
negative solution, for example, enter a negative number in the X: field before
solving the equation. Try 3\@@@OK@@˜@SOLVE@. The solution is now X: -
3.045.
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