HP 38g Graphing Calculator - Manual (Page 105)

Interpreting Results
After Solve has returned a solution, press {{INFO}} in the
Numeric view for more information. You will see one of the
following three messages. Press {{ ok }} to clear the message.
Messcige Condition
Zero The Solve aplet found a point where the value of the
equation (or the root of the expression) is zero within the
calculator's 12-digit accuracy.
Sign Reversal Solve found two points where the value of the equation has
opposite signs, but it cannot find a point in between where
the value is zero. This might be because
either the two points
are neighbors (they differ by one in the twelfth digit), or the
equation is not real-valued between the two points. Solve
returns the point where the value is closer to zero. If the
value of the equation is a continuous real function, this point
is Solve’s best approximation of an actual root.
Extremum Solve found a point where the value of the equation
approximates a local minimum (for positive values) or
maximum (for negative values). This point may or may not
be a root. Or: Solve stopped searching at
±9.99999999999E499, the largest number the calculator can
represent.
If Solve could not find a solution, you will see one of the
following two messages.
Message Condition
Bad Guess(es) No solution found. One or more of the initial guesses lie
outside the domain of the equation. Therefore, the solution
was not a real number or it caused an error.
Constant? No solution found. The value of the equation is the same at
every point sampled.
Solve 4-7