HP 17bll+ User Manual page 245

Case 2a:
have opposite
signs. The two estimates are
"neighbors".
Case 2c:
have the same
sign..
Case 3: The calculator displays:

The Solver is unable to begin its iterative search for a solution using
the current initial estimates (guesses). You might find a solution by
           
                
B: More About Calculations 245
Case 2b:
have opposite
signs. The two estimates are
far apart.