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The root- finder at work – HP 39g Graphing Calculator User Manual

Page 91

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If Solve could not find a solution, you will see one of the

following two messages.

Message

Condition

Bad Guess(es)

The initial guess lies outside the

domain of the equation. Therefore,
the solution was not a real number or

it caused an en'or.

Constant?

The value of the equation is the same

at every point sampled.

H I N T It is important to check the information relating to the solve

process. For example, the solution that the Solve aplet finds is
not a solution, but the closest that the function gets to zero.

Only by checking the information will you know that this is

the ca.se.

The Root-

Finder at work

You can watch the process of the root-finder calculating and
searching for a root. Immediately after pressing мавд:| to start
the root-finder, press any key except

|

on

]. Y

ou

will see two

intermediate guesses and, to the left, the sign of the expression

evaluated at each guess. For example:

-t 2 2.219330555745

- 1 21.31111111149

You can watch as the root-finder either finds a sign reversal or
converges on a local extrema or does not converge at all. If
there is no convergence in process, you might want to cancel
the operation (press | O

n

| ) and start over with a different initial

guess.

Solve aplet

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