Capture Trend Line equation in Excel Chart and extend to mutiple value

[resumes123]

have some data on an excel sheet which I had linked it to a chart. The data is monthly sales data for 12 months. The two columns are month no and sales amount. They are in column A and Column B.
I had linked the data to a chart and added a Trend line to it
I got a polynomial equation of 4th order for this Trend Line. It is
y = 6.833x4 - 66.33x3 + 227.1x2 - 208.6x + 152


y stands for sales which is in column B and x is the month no. which is column A
How can I capture this equation of the trend line in a string?
Currently, I have data for 12 months . But I would like to capture this Trend Line equation and extend it to another 6 months .
Hence, if I add more rows in Column A with month numbers, the column B should automatically be populated with Sales data ( projected or forecasted amounts )

The values in Column B ( for example, row 35 ) should read as
=(POWER($A35,4)*6.833)-(POWER($A35,3)*66.33)+(POWER($A35,2)*227.1)-(POWER($A35,1)*208.6) +152

How can I do that. Is there an Excel method or Excel VBA code to do that

Thanks

 

[Bong]

Presumably you know the data range that is being graphed. The Excel function, trend will do a linear fit. I think that for a polynomial fit you'll need to write your own (but I could certainly be wrong).

_________________
Bob Rashkin

 

[mintjulep]

LINEST() or LOGEST() functions. Both are array functions.