HP 32SII, Руководство пользователя

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7–8 Solving Equations
File name 32sii-Manual-E-0424
Printed Date : 2003/4/24 Size : 17.7 x 25.2 cm
to enter guesses before solving for T because in the first part of that
example you stored a value for T and solved for D. The value that was left
in T was a good (realistic) one, so it was used as a guess when solving
for T
.
If an equation does not allow certain values for the unknown, guesses
can prevent these values from occurring. For example,
y = t + log x
results in an error if
x
≤
0 (messages
12
or
12
).
In the following example, the equation has more than one root, but guesses
help find the desired root.
Example.
Using Guesses to Find a Root.
Using a rectangular piece of sheet metal 40 cm by 80 cm, form an open–top
box having a volume of 7500 cm
3
. You need to find the height of the box
(that is, the amount to be folded up along each of the four sides) that gives the
specified volume. A
taller box is preferred to a shorter one.
40
80
40_2 H
H
H
80_2 H H H