DPlot

I have a plot that has a hill and I put a slope line on the flatest part of the hill (using more fit curves). The new slope line I get how can I extend it to go from graph edge to graph edge?

With the "More Curve Fits" module the last screen gives you the opportunity to plot the equation. By default "using input X values" is checked. If you uncheck that option you can enter whatever start/stop X values you want.

Thank You so much