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 equationx2 – 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."