How to Do Single Variable Algebra in Excel

By Ryan Menezes

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Single variable algebra uses an equation to calculate the value of a single factor. For example, if your company determines a function to predict revenues over time, single variable algebra can suggests the time at which you'll hit a predicted revenue level. Excel solves these equations using the Solver Add-in, a data tool. The add in changes the value of one cell, which contains the single variable, to reach a target value, the other side of the algebraic equation.

Type your algebraic function into a cell, using a second cell reference as the single variable. For example, to type the function "2x^3 -2x^2 + 10," type the following into cell B1:

\= 2 * A1 ^ 3 - 2 * A1 ^ 2 + 10

Click "Solver" in the Data tab's Analysis group to launch the Solver add-in.

Type the function's target value in the window's "Value of:" box. For example, if the algebraic equation reads "2x^3 - 2x^2 + 10 = 20,000," type "20000."

Type the reference that you used for the single variable in the box labeled "By changing variable cells." With this example, type "A1."

Click "Solve" to calculate the variable's value. In this example, Excel inserts "21.8793" into cell A1.

Tips

If you to not see the Solver tool in the ribbon's Data tab, add it through the Excel Options window's Add-ins section.

Some equations have multiple solutions. If Excel returns an answer that is negative, very small or otherwise significantly different from your expected solution, insert a predicted value into the worksheet's "Value of" cell and run the solver tool again. With the above example, if you expect an answer close to "15," type "15" into cell A1 before running the tool.