AJP Excel Information

Re: Dynamic trend line

The chart contains 2 data series. One is linked to the data and therefore maintains the correct number of categories.
The other data series uses a Named Range as its data source.

The Trendline is plotted against the second data series and will update when new data is added.
This approach allows you to use all of the trend line types and their formatting options.

Named range ChartData =OFFSET(Sheet1!$A$2,0,1,COUNT(Sheet1!$B:$B),1)

This workbook contains an example.