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6–10 Entering and Evaluating Equations
File name 33s-English-Manual-040130-Publication(Edition 2).doc Page : 388
Printed Date : 2004/1/30 Size : 13.7 x 21.2 cm
Because many equations have two sides separated by "=", the basic value of an
equation is the
difference between the values of the two sides. For this calculation,
"=" in an equation essentially treated as "
–
". The value is a measure of how well
the equation balances.
The HP 33s has two keys for evaluating equations:
Ï
and
t
. Their
actions differ only in how they evaluate
assignment equations:
t
returns the value of the equation, regardless of the type of equation.
Ï
returns the value of the equation — unless it's an assignment–type
equation. For an assignment equation,
Ï
returns the value of the right
side only, and also "enters" that value into the variable on the left side — it
stores the value in the variable.
The following table shows the two ways to evaluate equations.
Type of Equation Result for Ï Result for t
Equality: g(x) = f(x)
Example:
x
2
+ y
2
= r
2
g(x) – f(x)
x
2
+ y
2
– r
2
Assignment: y = f(x)
Example:
A = 0.5
×
b x h
f(x)
0.5
×
b
×
h
y – f(x)
A – 0.5
×
b
×
h
Expression: f(x)
Example:
x
3
+ 1
f(x)
x
3
+ 1
Also stores the result in the left–hand variable, A for example.
To evaluate an equation:
1.
Display the desired equation. (See "Displaying and Selecting Equations"
above.)
2. Press
Ï
or
t
. The equation prompts for a value for each variable
needed. (If you've changed the number base, it's automatically changed back
to base 10.)
3. For each prompt, enter the desired value:
If the displayed value is good, press
¥
.
If you want a different value, type the value and press
¥
. (Also see
"Responding to Equation Prompts" later in this chapter.)