HP 35s HP 35s scientific calculator - User Guide - Page 123

Solving Equations

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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 x2 - 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." Solving Equations 7-1

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Solving Equations
7-1
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
x
2
– 3
y
= 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."