Extract Equation from Trendline

Hi,

Does anyone know if it is possible to extract the equation from a trend line? What I would like to do is the following:

1. Graph a bunch of data points
2. Add a trend line and display the equation on the chart (for example: Y = 3X+5)
3. Link cells in the spreadsheet to the equation (for example: cell A1 = 3 and cell B1 = 5)

The first 2 steps are easy, becuase there are standard excel tools to do that. the third step is what I'm not so sure.

The idea would be to have the value in the cells change, if the data being trended also changes.

Would anyone know if there is some VBA code that can do this?

thanks!