# Solving Equations; Solving An Equation - HP 35s User Manual

Scientific calculator.

7

## Solving Equations

In chapter 6 you saw how you can use
to find the value of the left–hand
variable in an assignment–type equation. Well, you can use SOLVE to find the value
of any variable in any type of equation.
For example, consider the equation
2
x
– 3y = 10
If you know the value of y in this equation, then SOLVE can solve for the unknown x.
If you know the value of x, then SOLVE can solve for the unknown y. This works for
"word problems" just as well:
Markup
Cost = Price
If you know any two of these variables, then SOLVE can calculate the value of the
third.
When the equation has only one variable, or when known values are supplied for
all variables except one, then to solve for x is to find a root of the equation. A root
of an equation occurs where an equality or assignment equation balances exactly,
or where an expression equation equals zero.

### Solving an Equation

To solve an equation (excluding built-in equations) for an unknown variable:
1. Press
and display the desired equation. If necessary, type the equation
as explained in chapter 6 under "Entering Equations into the Equation List."
7-1
Solving Equations  