How to Use a Root Solver in Excel

by Ryan Menezes
Excel's many functions include solving equations.

Excel's many functions include solving equations.

Microsoft Excel's solver tool changes the value in one cell to supply a desired result in another on whose contents the first depends. The tool has various practical applications, such as producing sales figures necessary to achieve a target profit. But it also has a pure mathematical application in finding the root, or solution of an equation. This is especially useful for higher order equations that are very difficult to solve manually.

1

Click "File" from Excel's menu bar.

2

Click "Options." The "Excel Options" window will open.

3

Click "Add-Ins" in the left pane. Click "Solver Add-in" from the right pane.

4

Click the "Go" button. The "Add-Ins" dialog box will open.

5

Check the box next to "Solver Add-in." Click "OK."

6

Type your equation into a cell, using a second cell as a reference. For instance, if your equation is "4x^3 + 2x^2 - 87 = -1," type into cell A1, "=4 * A2^3 + 2 * A2^2 - 87."

7

Click on the "Data" ribbon.

8

Click "Solver" from the "Analysis" tab. The "Solver Parameters" window will open.

9

Enter the reference of the cell into which you typed the formula in the "Set Objective:" box. In this example, type "A1."

10

Click the "Value of:" button.

11

Enter your target value in the "Value Of:" box. In this example, type "-1."

12

Type the formula's reference cell in the "By Changing Variable Cells:" box. In this example, type "A2."

13

Click "Solve." Excel will change both cells accordingly. In this example, cell A1 will change to "-1.00007," which is very close to "-1." Cell A2 will change to "2.623573," which is a root of the equation.

About the Author

Ryan Menezes is a professional writer and blogger. He has a Bachelor of Science in journalism from Boston University and has written for the American Civil Liberties Union, the marketing firm InSegment and the project management service Assembla. He is also a member of Mensa and the American Parliamentary Debate Association.

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