How do I improve Accuracy of trendlines?

[Tom21]

I am taking known data (4 points) and creating a trendling. I am selecting
the option to show the formula and R*R value, which is 1.0. I am charting
this equation and comparing it to the data used to create the formula, and to
the chart used to derive the formula. They are very different. Can I correct
this situation? If so, how? I have checked to make sure that I typed in the
correct formula. Where do I go from here?

 

[Jerry W. Lewis]

Right click on the equation and format to display scientific notation with 14
decimal places.

Also, make sure that your chart is an "XY (Scatter)" chart and not a "Line"
chart. The "Line" chart is very misleadingly named; it has nothing to do
with whether you want a line or not--rather it considers the x-data (if given
at all) to be category labels instead of numbers. Why it offers to fit a
trendline when it does not believe the x-data to be numeric is a mystery; but
when asked to do so, it assumes that the x-data are 1,2,3,... instead of the
values that you may have supplied. As a result, trendlines on "Line" charts
are usually worse than meaningless.

Jerry