Export Graph Trend Line Equation

The LINEST function will return the coefficients of a trendline to a worksheet.

Every available trendline in the chart (except moving average) is "linear" (linear in this context refers to a linear equation in the more advanced linear algebra sense, so it refers to much more than straight lines). The LINEST() help file http://office.microsoft.com/en-us/ex...in=HA010277524 has an example for a third order polynomial (just before example 1 about half way down), it should be easy to adapt it to a 2nd order polynomial.

If I understand correctly, this is usually because you have failed to follow the appropriate "array formula protocol" for entering an array formula like LINEST().

Select an appropriate horizontal range of cells, enter the LINEST() formula, the confirm with ctrl-shift-enter (not just enter). If you put TRUE of the fourth argument, then you need to select a larger block of cells to output the additional statistics (examples are in the help file above).

Assuming no typos, you refer to "this cell" singular -- suggesting that you have only selected one cell when entering the LINEST() function. For a 2nd order polynomial (3 parameters) with additional statistics, you will need to select a 4 row x 3 column (=12 cells) block before array-entering the LINEST() function. If you only select one cell, then you only get the upper left entry in the LINEST() array.