HP 33s User Manual page 102

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:
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,
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
Equality: g(x) = f(x)
2
Example: x + y
Assignment: y = f(x)
Example: A = 0.5
Expression: f(x)
3
Example: x + 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.)
Ï
2. Press
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
"Responding to Equation Prompts" later in this chapter.)
6–10
Entering and Evaluating Equations
Result for
2 2
= r
b x h
t
or . The equation prompts for a value for each variable
Ï
Ï
returns the value of the right
Ï
g(x) – f(x)
2 2
x + y
f(x)
0.5 b h
f(x)
3
x + 1
¥
.
t
and . Their
Result for
t
2
– r
y – f(x)
A – 0.5 b h
¥
. (Also see