How to Solve an Equation in Excel

“ I have a curve. I did its fitting using Excel and got an equation.

y = 2E+07x^-2.146

For y=60 what will be the value of x?

How can we solve this equation using Excel? ”

Lets look at how this can be solved using Excel.

Define the Problem

Usman formula is y = 2E+07x^-2.146

or expanded y = 2*10^7*x^-2.146

We can use Excel’s Goal Seek function to assist us here

Goal Seek is located in the Data, What-If Analysis, Goal Seek menu

Goal Seek is an inbuilt function in Excel that searches for a solution to a model/formula by iteratively trying source cell values until a solution is found.

Before we start, Excel doesn’t understand the concepts of x and y, but we can use cells for these instead

To use Goal Seek we need to put our formula into a cell.

Start a new file and in C3 (our y cell) type:  = 2*10^7*B3^-2.146

In B3 (our x cell): Put a value say 10

Note that C3 will show the solution of the formula for when x=10 or = 2*10^7*10^-2.146 = 142,899.277

Using Goal Seek

To use Goal Seek to find what value of x (B3) will result in y (C3) = 60,

Select C3

Goto the Data, What-If Analysis, Goal Seek menu

Set Cell: C3  – This is our y value cell

To value: 60  This is the value we want to achieve

By changing cell: B3 – This is our x value cell

Click OK when ready

Excel shows us that it has found a solution and that y (C3) =60 when x (B3) = 374.60

Select OK to save the result

Select Cancel to return to the previous value