HP -15C Owner's Handbook Manual page 190

190 Section 13: Finding the Roots of an Equation
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It seems reasonable that either a tall, narrow box or a short, flat box could
be formed having the desired volume. Because the taller box is preferred,
larger initial estimates of the height are reasonable. However, heights
greater than 2 decimeters are not physically possible (because the metal is
only 4 decimeters wide). Initial estimates of 1 and 2 decimeters are
therefore appropriate.
Find the desired height:
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1.0000
2
1.5000
1.5000
0.0000
30
20
(x – 6) x.
8
40
20 ((x – 6) x + 8) x.
4
20 4 ((x – 6) x + 8) x.
7
48
5
30
Run mode.
Initial estimates.
The desired height.
Previous estimate.
f(x) at root.