HP 35s Scientific Calculator - Manual (Page 132)

7-10 Solving Equations
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.
If H is the height, then the length of the box is (80 – 2H) and the width is (40 – 2H).
The volume V is:
V = ( 80 – 2H ) × (40 – 2H ) × H
which you can simplify and enter as
V= ( 40 – H ) × ( 20 – H ) Ч 4 Ч H
Type in the equation:
Keys: Display: Description:


_ Selects Equation mode and starts
the equation
4
HÕ
_
40
80
40_2 H
H
H
80_2 H H H